Linux IPv6 HOWTO (en)
Peter Bieringer
pb at bieringer dot de
Revision History
Revision 0.67wip 2017-07-14 PB
Revision 0.66 2014-05-15 PB
Revision 0.65 2009-12-13 PB
Revision 0.64 2009-06-11 PB
Revision 0.60 2007-05-31 PB
Revision 0.51 2006-11-08 PB
Abstract
The goal of the Linux IPv6 HOWTO is to answer both basic and advanced questions
about IPv6 on the Linux operating system. This HOWTO will provide the reader
with enough information to install, configure, and use IPv6 applications on
Linux machines. Intermediate releases of this HOWTO are available at
mirrors.bieringer.de or mirrors.deepspace6.net. See also revision_history for
changes.
-------------------------------------------------------------------------------
Table of Contents
1._General
1._Copyright,_license_and_others
1.1._Copyright
1.2._License
1.3._About_the_author
2._Category
3._Version,_History_and_To-Do
3.1._Version
3.2._History
3.3._To-Do
4._Translations
4.1._To_language
5._Technical
5.1._Original_source_of_this_HOWTO
5.2._On-line_references_to_the_HTML_version_of_this_HOWTO_
(linking/anchors)
6._Preface
6.1._How_many_versions_of_a_Linux_&_IPv6_related_HOWTO_are
floating_around?
7._Used_terms,_glossary_and_shortcuts
7.1._Network_related
7.2._Document_related
8._Requirements_for_using_this_HOWTO
8.1._Personal_prerequisites
8.2._Linux_operating_system_compatible_hardware
2._Basics
1._What_is_IPv6?
2._History_of_IPv6_in_Linux
2.1._Beginning
2.2._In_between
2.3._Current
2.4._Future
3._What_do_IPv6_addresses_look_like?
4._FAQ_(Basics)
4.1._Why_is_the_name_IPv6_and_not_IPv5_as_successor_for_IPv4?
4.2._IPv6_addresses:_why_such_a_high_number_of_bits?
4.3._IPv6_addresses:_why_so_small_a_number_of_bits_on_a_new
design?
3._Address_types
1._Addresses_without_a_special_prefix
1.1._Localhost_address
1.2._Unspecified_address
1.3._IPv6_address_with_embedded_IPv4_address
2._Network_part,_also_known_as_prefix
2.1._Link_local_address_type
2.2._Site_local_address_type
2.3._Unique_Local_IPv6_Unicast_Addresses
2.4._Global_address_type_"(Aggregatable)_global_unicast"
2.5._Multicast_addresses
2.6._Anycast_addresses
3._Address_types_(host_part)
3.1._Automatically_computed_(also_known_as_stateless)
3.2._Manually_set
4._Prefix_lengths_for_routing
4.1._Prefix_lengths_(also_known_as_"netmasks")
4.2._Matching_a_route
4._IPv6-ready_system_check
1._IPv6-ready_kernel
1.1._Check_for_IPv6_support_in_the_current_running_kernel
1.2._Try_to_load_IPv6_module
1.3._Compile_kernel_with_IPv6_capabilities
1.4._IPv6-ready_network_devices
2._IPv6-ready_network_configuration_tools
2.1._net-tools_package
2.2._iproute_package
3._IPv6-ready_test/debug_programs
3.1._IPv6_ping
3.2._IPv6_traceroute6
3.3._IPv6_tracepath6
3.4._IPv6_tcpdump
4._IPv6-ready_programs
5._IPv6-ready_client_programs_(selection)
5.1._Checking_DNS_for_resolving_IPv6_addresses
5.2._IPv6-ready_telnet_clients
5.3._IPv6-ready_ssh_clients
5.4._IPv6-ready_web_browsers
6._IPv6-ready_server_programs
7._FAQ_(IPv6-ready_system_check)
7.1._Using_tools
5._Configuring_interfaces
1._Different_network_devices
1.1._Physically_bounded
1.2._Virtually_bounded
2._Bringing_interfaces_up/down
2.1._Using_"ip"
2.2._Using_"ifconfig"
6._Configuring_IPv6_addresses
1._Displaying_existing_IPv6_addresses
1.1._Using_"ip"
1.2._Using_"ifconfig"
2._Add_an_IPv6_address
2.1._Using_"ip"
2.2._Using_"ifconfig"
3._Removing_an_IPv6_address
3.1._Using_"ip"
3.2._Using_"ifconfig"
4._Automatic_IPv6_Address_Configuration
5._Enable_Privacy_Extension
5.1._Enable_Privacy_Extension_using_sysctl
5.2._Enable_Privacy_Extension_using_NetworkManager
5.3._Test_real_use_of_Privacy_Extension_IPv6_Addresses
7._Configuring_normal_IPv6_routes
1._Displaying_existing_IPv6_routes
1.1._Using_"ip"
1.2._Using_"route"
2._Add_an_IPv6_route_through_a_gateway
2.1._Using_"ip"
2.2._Using_"route"
3._Removing_an_IPv6_route_through_a_gateway
3.1._Using_"ip"
3.2._Using_"route"
4._Add_an_IPv6_route_through_an_interface
4.1._Using_"ip"
4.2._Using_"route"
5._Removing_an_IPv6_route_through_an_interface
5.1._Using_"ip"
5.2._Using_"route"
6._FAQ_for_IPv6_routes
6.1._Support_of_an_IPv6_default_route
8._Neighbor_Discovery
1._Displaying_neighbors_using_â€ipâ€
2._Manipulating_neighbors_table_using_â€ipâ€
2.1._Manually_add_an_entry
2.2._Manually_delete_an_entry
2.3._More_advanced_settings
9._Configuring_IPv6-in-IPv4_tunnels
1._Types_of_tunnels
1.1._Static_point-to-point_tunneling
1.2._Automatically_tunneling
1.3._6to4-Tunneling
1.4._UDP_encapsulated_IPv6_tunneling
2._Displaying_existing_tunnels
2.1._Using_"ip"
2.2._Using_"route"
3._Setup_of_point-to-point_tunnel
3.1._Add_point-to-point_tunnels
3.2._Removing_point-to-point_tunnels
3.3._Numbered_point-to-point_tunnels
4._Setup_of_6to4_tunnels
4.1._Add_a_6to4_tunnel
4.2._Remove_a_6to4_tunnel
10._Configuring_IPv4-in-IPv6_tunnels
1._Displaying_existing_tunnels
2._Setup_of_point-to-point_tunnel
3._Removing_point-to-point_tunnels
11._Kernel_settings_in_/proc-filesystem
1._How_to_access_the_/proc-filesystem
1.1._Using_â€catâ€_and_â€echoâ€
1.2._Using_â€sysctlâ€
1.3._Values_found_in_/proc-filesystems
2._Entries_in_/proc/sys/net/ipv6/
2.1._conf/default/*
2.2._conf/all/*
2.3._conf/interface/*
2.4._neigh/default/*
2.5._neigh/interface/*
2.6._route/*
3._IPv6-related_entries_in_/proc/sys/net/ipv4/
3.1._ip_*
3.2._tcp_*
3.3._icmp_*
3.4._others
4._IPv6-related_entries_in_/proc/net/
4.1._if_inet6
4.2._ipv6_route
4.3._sockstat6
4.4._tcp6
4.5._udp6
4.6._igmp6
4.7._raw6
4.8._ip6_flowlabel
4.9._rt6_stats
4.10._snmp6
4.11._ip6_tables_names
12._Netlink-Interface_to_kernel
13._Address_Resolver_&_Selection
14._Network_debugging
1._Server_socket_binding
1.1._Using_â€netstatâ€_for_server_socket_binding_check
2._Examples_for_tcpdump_packet_dumps
2.1._Router_discovery
2.2._Neighbor_discovery
15._Support_for_persistent_IPv6_configuration_in_Linux_distributions
1._Red_Hat_Linux_and_â€clonesâ€
1.1._Test_for_IPv6_support_of_network_configuration_scripts
1.2._Short_hint_for_enabling_IPv6_on_current_RHL_7.1,_7.2,_7.3,
...
2._SuSE_Linux
2.1._SuSE_Linux_7.3
2.2._SuSE_Linux_8.0
2.3._SuSE_Linux_8.1
3._Debian_Linux
3.1._Further_information
16._Auto-configuration
1._Stateless_auto-configuration_out-of-the-box
2._Stateless_auto-configuration_using_Router_Advertisement_Daemon_
(radvd)
3._Dynamic_Host_Configuration_Protocol_v6_(DHCPv6)
17._Mobility
1._Common_information
1.1._Node_Mobility
1.2._Network_Mobility
1.3._Links
18._Firewalling
1._Firewalling_using_netfilter6
1.1._More_information
2._Preparation
2.1._Get_sources
2.2._Extract_sources
2.3._Apply_latest_iptables/IPv6-related_patches_to_kernel_source
2.4._Configure,_build_and_install_new_kernel
2.5._Rebuild_and_install_binaries_of_iptables
3._Usage_of_ip6tables
3.1._Check_for_support
3.2._Learn_how_to_use_ip6tables
3.3._Examples
4._Network_Address_Translation_(NAT)_using_netfilter6
4.1._IPv6_Masquerading
4.2._IPv6_Destination_NAT
4.3._IPv6_Port_Forwarding
5._Firewalling_using_nftables
5.1._Preparation_for_nftables_usage
5.2._Basic_nftables_configuration
5.3._Simple_filter_policy_with_nftables_using_only_table_â€inetâ€
5.4._Filter_policy_with_nftables_using_tables_â€ipâ€,_â€ip6â€_and
â€inetâ€
19._Security
1._Node_security
2._Access_limitations
3._IPv6_security_auditing
3.1._Legal_issues
3.2._Security_auditing_using_IPv6-enabled_netcat
3.3._Security_auditing_using_IPv6-enabled_nmap
3.4._Security_auditing_using_IPv6-enabled_strobe
3.5._Security_auditing_using_online_tools
3.6._Audit_results
20._Encryption_and_Authentication
1._Modes_of_using_encryption_and_authentication
1.1._Transport_mode
1.2._Tunnel_mode
2._Support_in_kernel_(ESP_and_AH)
2.1._Support_in_vanilla_Linux_kernel_2.4.x
2.2._Support_in_vanilla_Linux_kernel_2.6.x
3._Automatic_key_exchange_(IKE)
3.1._IKE_daemon_â€racoonâ€
3.2._IKE_daemon_â€plutoâ€
4._Additional_informations:
21._Quality_of_Service_(QoS)
1._General
2._Linux_QoS_using_â€tcâ€
2.1._Example_for_a_constant_bitrate_queuing
22._Hints_for_IPv6-enabled_daemons
1._Berkeley_Internet_Name_Domain_(BIND)_daemon_â€namedâ€
1.1._Listening_on_IPv6_addresses
1.2._IPv6_enabled_Access_Control_Lists_(ACL)
1.3._Sending_queries_with_dedicated_IPv6_address
1.4._Per_zone_defined_dedicated_IPv6_addresses
1.5._IPv6_DNS_zone_files_examples
1.6._Serving_IPv6_related_DNS_data
1.7._Checking_IPv6-enabled_connect
2._Internet_super_daemon_(xinetd)
3._Webserver_Apache2_(httpd2)
3.1._Listening_on_IPv6_addresses
4._Router_Advertisement_Daemon_(radvd)
4.1._Configuring_radvd
4.2._Debugging
5._Dynamic_Host_Configuration_v6_Server_(dhcp6s)
5.1._Configuration_of_the_DHCPv6_server_(dhcp6s)
5.2._Configuration_of_the_DHCPv6_client_(dhcp6c)
5.3._Usage
5.4._Debugging
6._ISC_Dynamic_Host_Configuration_Server_(dhcpd)
6.1._Configuration_of_the_ISC_DHCP_server_for_IPv6_(dhcpd)
6.2._Usage
7._DHCP_Server_Dibbler
7.1._Configuration_of_the_Dibbler_DHCP_server_for_IPv6
7.2._Usage
8._tcp_wrapper
8.1._Filtering_capabilities
8.2._Which_program_uses_tcp_wrapper
8.3._Usage
8.4._Logging
9._vsftpd
9.1._Listening_on_IPv6_addresses
10._proftpd
10.1._Listening_on_IPv6_addresses
11._Other_daemons
23._Programming
1._Programming_using_C-API
1.1._Address_Structures
1.2._Lookup_Functions
1.3._Quirks_Encountered
1.4._Putting_It_All_Together_(A_Client-Server_Programming
Example)
2._Other_programming_languages
2.1._JAVA
2.2._Perl
24._Interoperability
25._Further_information_and_URLs
1._Paper_printed_books,_articles,_online_reviews_(mixed)
1.1._Printed_Books_(English)
1.2._Articles,_eBooks,_Online_Reviews_(mixed)
1.3._Science_Publications_(abstracts,_bibliographies,_online
resources)
1.4._Others
2._Conferences,_Meetings,_Summits
2.1._2004
3._Online_information
3.1._Join_the_IPv6_backbone
3.2._Latest_news_and_URLs_to_other_documents
3.3._Protocol_references
3.4._More_information
3.5._By_countries
3.6._By_operating_systems
3.7._IPv6_Security
3.8._Application_lists
4._IPv6_Infrastructure
4.1._Statistics
4.2._Internet_Exchanges
4.3._Tunnel_broker
4.4._Native_IPv6_Services
5._Maillists
6._Online_tools
6.1._Testing_tools
6.2._Information_retrievement
6.3._IPv6_Looking_Glasses
6.4._Helper_applications
7._Trainings,_Seminars
8._'The_Online_Discovery'_...
26._Revision_history_/_Credits_/_The_End
1._Revision_history
1.1._Releases_0.x
2._Credits
2.1._Major_credits
2.2._Other_credits
3._The_End
Chapter 1. General
Table of Contents
1._Copyright,_license_and_others
1.1._Copyright
1.2._License
1.3._About_the_author
2._Category
3._Version,_History_and_To-Do
3.1._Version
3.2._History
3.3._To-Do
4._Translations
4.1._To_language
5._Technical
5.1._Original_source_of_this_HOWTO
5.2._On-line_references_to_the_HTML_version_of_this_HOWTO_(linking/
anchors)
6._Preface
6.1._How_many_versions_of_a_Linux_&_IPv6_related_HOWTO_are_floating
around?
7._Used_terms,_glossary_and_shortcuts
7.1._Network_related
7.2._Document_related
8._Requirements_for_using_this_HOWTO
8.1._Personal_prerequisites
8.2._Linux_operating_system_compatible_hardware
Information about available translations you will find in section Translations.
1. Copyright, license and others
1.1. Copyright
Written and Copyright (C) 2001-2017 by Peter Bieringer
1.2. License
This Linux IPv6 HOWTO is published under GNU GPL version 2:
The Linux IPv6 HOWTO, a guide how to configure and use IPv6 on Linux systems.
Copyright © 2001-2017 Peter Bieringer
This documentation is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the Free
Software Foundation; either version 2 of the License, or (at your option) any
later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 51 Franklin
Street, Fifth Floor, Boston, MA 02110, USA.
1.3. About the author
1.3.1. Internet/IPv6 history of the author
* 1993: I got in contact with the Internet using console based e-mail and news
client (e.g. look for â€e91abier†on groups.google.com, that's me).
* 1996: I got a request for designing a course on IPv6, including a workshop
with the Linux operating system.
* 1997: Started writing a guide on how to install, configure and use IPv6 on
Linux systems, called IPv6_&_Linux_-_HowTo (see IPv6_&_Linux_-_HowTo/
History for more information).
* 2001: Started writing this new Linux IPv6 HOWTO.
1.3.2. Contact
The author can be contacted via e-mail at <pb at bieringer dot de> and also via
his homepage.
He's currently living in Munich / Bavaria / Germany / Europe / Earth.
2. Category
This HOWTO should be listed in category â€Networking/Protocolsâ€.
3. Version, History and To-Do
3.1. Version
The current version is shown at the beginning of the document.
For other available versions/translations see also http://www.bieringer.de/
linux/IPv6/.
3.2. History
3.2.1. Major history
2001-11-30: Starting to design new HOWTO.
2002-01-02: A lot of content completed, first public release of chapter 1
(version 0.10).
2002-01-14: More completed, some reviews, public release of the whole document
(version 0.14).
2002-08-16: Polish translation is in progress
2002-10-31: Chinese translation is available (see Translations for more)
2002-11-10: German translation is in progress
2003-02-10: German translation is available
2003-04-09: French translation is in progress
2003-05-09: French translation is available
2003-10-16: Italian translation is in progress
2004-03-12: Italian translation is available
2004-06-18: Greek translation is in progress
2005-07-25: Turkish translation is availble
2007-03-28: Portuguese-Brazil translation is in progress
2008-07-30: Spanish translation is available (lost, URL no longer valid)
2011-05-09: Portuguese-Brazil translation is again in progress
3.2.2. Full history
See revision_history at the end of this document.
3.3. To-Do
* Fill in missing content
* Finishing grammar checking
4. Translations
Translations always have to contain the URL, version number and copyright of
the original document (but yours, too). Pls. don't translate the original
changelog, this is not very useful - also do not translate the full section
about available translations, can be run out-of-date, add an URL to this
section here in the English howto.
Looks like the document's change frequency is mostly less than once per month.
Since version 0.27 it looks like that most of the content contributed by me has
been written. Translations always have to use the English version as source.
4.1. To language
Note: an overview with URLs can be found at http://www.bieringer.de/linux/
IPv6/.
4.1.1. Chinese
A Chinese translation by Burma Chen <expns at yahoo dot com> (announced to me
at 2002-10-31) can be found on the TLDP: http://www.ibiblio.org/pub/Linux/docs/
HOWTO/translations/zh/Linux-IPv6-HOWTO.txt.gz_(g'zipped_txt). It's a snapshot
translation, don't know whether kept up-to-date.
4.1.2. Polish
Since 2002-08-16 a Polish translation was started and is still in progress by
Lukasz Jokiel <Lukasz dot Jokiel at klonex dot com dot pl>. Taken source: CVS-
version 1.29 of LyX file, which was source for howto version 0.27. Status is
still work-in-progress (2004-08-30).
4.1.3. German
With 2002-11-10 a German translation was started by Georg Käfer <gkaefer at gmx
dot at> and the first public version was published 2003-02-10. It's originally
available on Deep Space 6 at http://mirrors.deepspace6.net/Linux+IPv6-HOWTO-de/
(mirrored e.g. on http://mirrors.bieringer.de/Linux+IPv6-HOWTO-de/). This
version will stay up-to-date as much as possible.
4.1.4. French
With 2003-04-09 a French translation was started by Michel Boucey <mboucey at
free dot fr> and the first public version was published 2003-05-09. It's
originally available on Deep Space 6 at http://mirrors.deepspace6.net/
Linux+IPv6-HOWTO-fr/ (mirrored e.g. on http://mirrors.bieringer.de/Linux+IPv6-
HOWTO-fr/).
4.1.5. Spanish
A member of the MontevideoLibre, a project in Uruguay (South America) started
the translation into Spanish in wiki format some time ago, but the URL is no
longer available.
4.1.6. Italian
With 2003-10-16 a Italian translation was started by Michele Ferritto <m dot
ferritto at virgilio dot it> for the ILDP (Italian Linux Documentation Project)
and the first public version was published 2004-03-12. It's originally
available on the ILDP at http://www.pluto.it/ildp/howto/ipv6.html.
4.1.7. Japanese
On 2003-05-14 Shino Taketani <shino_1305 at hotmail dot com> send me a note
that he planned to translate the HowTo into Japanese.
4.1.8. Greek
On 2004-06-18 Nikolaos Tsarmpopoulos <ntsarb at uth dot gr> send me a note that
he planned to translate the HowTo into Greek.
4.1.9. Turkish
On 2005-07-18 Necdet Yucel <nyucel at comu dot edu dot tr> send me a note that
a Turkish translation is available. It's a snapshot translation (currently of
0.61) and can be found at http://docs.comu.edu.tr/howto/ipv6-howto.html.
4.1.10. Portuguese-Brazil
On 2011-05-06 Gustavo Mendes de Carvalho <gmcarvalho at gmail dot com> start to
translate the HowTo in Portuguese-Brazil. The first try in 2007 by Claudemir da
Luz <claudemir dot daluz at virtuallink dot com dot br> was never finished.
5. Technical
5.1. Original source of this HOWTO
This HOWTO is currently written with LyX version 2.2.2 on a Fedora 25 Linux
system with template SGML/XML (DocBook book). It's available on github_/_tLDP_/
Linux-IPv6 for contribution.
5.1.1. Code line wrapping
Code line wrapping is done using selfmade utility â€lyxcodelinewrapper.plâ€, you
can get it from GitHub for your own usage: github_/_tLDP_/_Linux-IPv6
5.1.2. SGML generation
SGML/XML is generated using export function in LyX.
5.2. On-line references to the HTML version of this HOWTO (linking/anchors)
5.2.1. Master index page
Generally, a reference to the master index page is recommended.
5.2.2. Dedicated pages
Because the HTML pages are generated out of the SGML file, the HTML filenames
turn out to be quite random. However, some pages are tagged in LyX, resulting
in static names. These tags are useful for references and shouldn't be changed
in the future.
If you think that I have forgotten a tag, please let me know, and I will add
it.
6. Preface
Some things first:
6.1. How many versions of a Linux & IPv6 related HOWTO are floating around?
Including this, there are three (3) HOWTO documents available. Apologies, if
that is too many ;-)
6.1.1. Linux IPv6 FAQ/HOWTO (outdated)
The first IPv6 related document was written by Eric Osborne and called Linux
IPv6_FAQ/HOWTO (please use it only for historical issues). Latest version was
3.2.1 released July, 14 1997.
Please help: if someone knows the date of birth of this HOWTO, please send me
an e-mail (information will be needed in â€historyâ€).
6.1.2. IPv6 & Linux - HowTo (maintained)
There exists a second version called IPv6_&_Linux_-_HowTo written by me
(Peter Bieringer) in pure HTML. It was born April 1997 and the first English
version was published in June 1997. I will continue to maintain it, but it will
slowly fade (but not full) in favour of the Linux IPv6 HOWTO you are currently
reading.
6.1.3. Linux IPv6 HOWTO (this document)
Because the IPv6_&_Linux_-_HowTo is written in pure HTML it's not really
compatible with the The_Linux_Documentation_Project_(TLDP). I (Peter Bieringer)
got a request in late November 2001 to rewrite the IPv6_&_Linux_-_HowTo in
SGML. However, because of the discontinuation of that HOWTO (Future_of_IPv6
&_Linux_-_HowTo), and as IPv6 is becoming more and more standard, I decided
to write a new document covering basic and advanced issues which will remain
important over the next few years. More dynamic and some advanced content will
be still found further on in the second HOWTO (IPv6_&_Linux_-_HowTo).
7. Used terms, glossary and shortcuts
7.1. Network related
Base 10
Well known decimal number system, represent any value with digit 0-9.
Base 16
Usually used in lower and higher programming languages, known also as
hexadecimal number system, represent any value with digit 0-9 and char A-
F (case insensitive).
Base 85
Representation of a value with 85 different digits/chars, this can lead
to shorter strings but never seen in the wild.
Bit
Smallest storage unit, on/true (1) or off/false (0)
Byte
Mostly a collection of 8 (but not really a must - see older computer
systems) bits
Device
Here, hardware of network connection, see also NIC
Dual homed host
A dual homed host is a node with two network (physical or virtual)
interfaces on two different links, but does not forward any packets
between the interfaces.
Host
Generally a single homed host on a link. Normally it has only one active
network interface, e.g. Ethernet or (not and) PPP.
Interface
Mostly same as â€deviceâ€, see also NIC
IPÂ Header
Header of an IP packet (each network packet has a header, kind of is
depending on network layer)
Link
A link is a layer 2 network packet transport medium, examples are
Ethernet, Token Ring, PPP, SLIP, ATM, ISDN, Frame Relay,...
Node
A node is a host or a router.
Octet
A collection of 8 real bits, today also similar to â€byteâ€.
Port
Information for the TCP/UDP dispatcher (layer 4) to transport information
to upper layers
Protocol
Each network layer contains mostly a protocol field to make life easier
on dispatching transported information to upper layer, seen in layer 2
(MAC) and 3 (IP)
Router
A router is a node with two or more network (physical or virtual)
interfaces, capable of forwarding packets between the interfaces.
Socket
An IP socket is defined by source and destination IP addresses and Ports
and (binding)
Stack
Network related a collection of layers
Subnetmask
IP networks uses bit masks to separate local networks from remote ones
Tunnel
A tunnel is typically a point-to-point connection over which packets are
exchanged which carry the data of another protocol, e.g. an IPv6-in-IPv4
tunnel.
7.1.1. Shortcuts
ACL
Access Control List
API
Application Programming Interface
ASIC
Application Specified Integrated Circuit
BSD
Berkeley Software Distribution
CAN-Bus
Controller Area Network Bus (physical bus system)
ISP
Internet Service Provider
KAME
Project - a joint effort of six companies in Japan to provide a free IPv6
and IPsec (for both IPv4 and IPv6) stack for BSD variants to the world
www.kame.net
LIR
Local Internet Registry
NIC
Network Interface Card
RFC
Request For Comments - set of technical and organizational notes about
the Internet
USAGI
UniverSAl playGround for Ipv6 Project - works to deliver the production
quality IPv6 protocol stack for the Linux system.
7.2. Document related
7.2.1. Long code line wrapping signal char
The special character â€Â¬â€ is used for signaling that this code line is wrapped
for better viewing in PDF and PS files.
7.2.2. Placeholders
In generic examples you will sometimes find the following:
<myipaddress>
For real use on your system command line or in scripts this has to be replaced
with relevant content (removing the < and > of course), the result would be
e.g.
1.2.3.4
7.2.3. Commands in the shell
Commands executable as non-root user begin with $, e.g.
$ whoami
Commands executable as root user begin with #, e.g.
# whoami
8. Requirements for using this HOWTO
8.1. Personal prerequisites
8.1.1. Experience with Unix tools
You should be familiar with the major Unix tools e.g. grep, awk, find, ... ,
and know about their most commonly used command-line options.
8.1.2. Experience with networking theory
You should know about layers, protocols, addresses, cables, plugs, etc. If you
are new to this field, here is one good starting point for you: http://
www.rigacci.org/docs/biblio/online/intro_to_networking/book1.htm
8.1.3. Experience with IPv4 configuration
You should definitely have some experience in IPv4 configuration, otherwise it
will be hard for you to understand what is really going on.
8.1.4. Experience with the Domain Name System (DNS)
Also you should understand what the Domain Name System (DNS) is, what it
provides and how to use it.
8.1.5. Experience with network debugging strategies
You should at least understand how to use tcpdump and whatit can show you.
Otherwise, network debugging will very difficult for you.
8.2. Linux operating system compatible hardware
Surely you wish to experiment with real hardware, and not only read this HOWTO
to fall asleep here and there. ;-7)
Chapter 2. Basics
Table of Contents
1._What_is_IPv6?
2._History_of_IPv6_in_Linux
2.1._Beginning
2.2._In_between
2.3._Current
2.4._Future
3._What_do_IPv6_addresses_look_like?
4._FAQ_(Basics)
4.1._Why_is_the_name_IPv6_and_not_IPv5_as_successor_for_IPv4?
4.2._IPv6_addresses:_why_such_a_high_number_of_bits?
4.3._IPv6_addresses:_why_so_small_a_number_of_bits_on_a_new_design?
1. What is IPv6?
IPv6 is a new layer 3 protocol which will supersede IPv4 (also known as IP).
IPv4 was designed a long time ago (RFC_760_/_Internet_Protocol from January
1980) and since its inception, there have been many requests for more addresses
and enhanced capabilities. Latest RFC is RFC_2460_/_Internet_Protocol_Version_6
Specification. Major changes in IPv6 are the redesign of the header, including
the increase of address size from 32 bits to 128 bits. Because layer 3 is
responsible for end-to-end packet transport using packet routing based on
addresses, it must include the new IPv6 addresses (source and destination),
like IPv4.
For more information about the IPv6 history take a look at older IPv6 related
RFCs listed e.g. at SWITCH_IPv6_Pilot_/_References.
2. History of IPv6 in Linux
The years 1992, 1993 and 1994 of the IPv6 History (in general) are covered by
the following document: IPv6_or_IPng_(IP_next_generation).
To-do: better time-line, more content...
2.1. Beginning
The first IPv6 related network code was added to the Linux kernel 2.1.8 in
November 1996 by Pedro Roque. It was based on the BSD API:
diff -u --recursive --new-file v2.1.7/linux/include/linux/in6.h
¬ linux/include/linux/in6.h
--- v2.1.7/linux/include/linux/in6.h Thu Jan 1 02:00:00 1970
+++ linux/include/linux/in6.h Sun Nov 3 11:04:42 1996
@@ -0,0 +1,99 @@
+/*
+ * Types and definitions for AF_INET6
+ * Linux INET6 implementation
+ * + * Authors:
+ * Pedro Roque <******>
+ *
+ * Source:
+ * IPv6 Program Interfaces for BSD Systems
+ * <draft-ietf-ipngwg-bsd-api-05.txt>
The shown lines were copied from patch-2.1.8 (e-mail address was blanked on
copy&paste).
2.2. In between
Because of lack of manpower, the IPv6 implementation in the kernel was unable
to follow the discussed drafts or newly released RFCs. In October 2000, a
project was started in Japan, called USAGI, whose aim was to implement all
missing, or outdated IPv6 support in Linux. It tracks the current IPv6
implementation in FreeBSD made by the KAME_project. From time to time they
create snapshots against current vanilla Linux kernel sources.
Until kernel development series 2.5.x was started, the USAGI patch was so big,
that Linux networking maintainers were unable to include it completly in the
production source of the Linux kernel 2.4.x series.
During kernel development series 2.5.x, USAGI tried to insert all of their
current extensions into this.
2.3. Current
Many of the long-term developed IPv6 related patches by USAGI and others are
integrated into vanilla kernel series 2.6.x.
2.4. Future
USAGI and others are still working on implementation of newer features like
mobililty and others. From time to time, new extension patches are released and
also integration into vanilla kernel series is made.
3. What do IPv6 addresses look like?
As previously mentioned, IPv6 addresses are 128 bits long. This number of bits
generates very high decimal numbers with up to 39 digits:
2^128-1: 340282366920938463463374607431768211455
Such numbers are not really addresses that can be memorized. Also the IPv6
address schema is bitwise oriented (just like IPv4, but that's not often
recognized). Therefore a better notation of such big numbers is hexadecimal. In
hexadecimal, 4 bits (also known as â€nibbleâ€) are represented by a digit or
character from 0-9 and a-f (10-15). This format reduces the length of the IPv6
address to 32 characters.
2^128-1: 0xffffffffffffffffffffffffffffffff
This representation is still not very convenient (possible mix-up or loss of
single hexadecimal digits), so the designers of IPv6 chose a hexadecimal format
with a colon as separator after each block of 16 bits. In addition, the leading
"0x" (a signifier for hexadecimal values used in programming languages) is
removed:
2^128-1: ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff
A usable address (see address types later) is e.g.:
2001:0db8:0100:f101:0210:a4ff:fee3:9566
For simplifications, leading zeros of each 16 bit block can be omitted:
2001:0db8:0100:f101:0210:a4ff:fee3:9566 ->
¬ 2001:db8:100:f101:210:a4ff:fee3:9566
One sequence of 16 bit blocks containing only zeroes can be replaced with “::“.
But not more than one at a time, otherwise it is no longer a unique
representation.
2001:0db8:100:f101:0:0:0:1 -> 2001:db8:100:f101::1
The biggest reduction is seen by the IPv6 localhost address:
0000:0000:0000:0000:0000:0000:0000:0001 -> ::1
There is also a so-called compact (base85 coded) representation defined in RFC
1924_/_A_Compact_Representation_of_IPv6_Addresses (published on 1. April 1996),
never seen in the wild, probably an April fool's joke, but here is an example:
# ipv6calc --addr_to_base85 2001:0db8:0100:f101:0210:a4ff:fee3:9566
9R}vSQZ1W=9A_Q74Lz&R
Info: ipv6calc is an IPv6 address format calculator and converter
program and can be found here: ipv6calc_homepage (Mirror)
4. FAQ (Basics)
4.1. Why is the name IPv6 and not IPv5 as successor for IPv4?
On any IP header, the first 4 bits are reserved for protocol version. So
theoretically a protocol number between 0 and 15 is possible:
* 4: is already used for IPv4
* 5: is reserved for the Stream Protocol (STP, RFC_1819_/_Internet_Stream
Protocol_Version_2) (which never really made it to the public)
The next free number was 6. Hence IPv6 was born!
4.2. IPv6 addresses: why such a high number of bits?
During the design of IPv4, people thought that 32 bits were enough for the
world. Looking back into the past, 32 bits were enough until now and will
perhaps be enough for another few years. However, 32 bits are not enough to
provide each network device with a global address in the future. Think about
mobile phones, cars (including electronic devices on its CAN-bus), toasters,
refrigerators, light switches, and so on...
So designers have chosen 128 bits, 4 times more in length than in IPv4 today.
The usable size is smaller than it may appear however. This is because in the
currently defined address schema, 64 bits are used for interface identifiers.
The other 64 bits are used for routing. Assuming the current strict levels of
aggregation (/48, /32, ...), it is still possible to â€run out†of space, but
hopefully not in the near future.
See also for more information RFC_1715_/_The_H_Ratio_for_Address_Assignment
Efficiency and RFC_3194_/_The_Host-Density_Ratio_for_Address_Assignment
Efficiency.
4.3. IPv6 addresses: why so small a number of bits on a new design?
While, there are (possibly) some people (only know about Jim Fleming...) on the
Internet who are thinking about IPv8 and IPv16, their design is far away from
acceptance and implementation. In the meantime 128 bits was the best choice
regarding header overhead and data transport. Consider the minimum Maximum
Transfer Unit (MTU) in IPv4 (576 octets) and in IPv6 (1280 octets), the header
length in IPv4 is 20 octets (minimum, can increase to 60 octets with IPv4
options) and in IPv6 is 40 octets (fixed). This is 3.4 % of minimum MTU in IPv4
and 3.1 % of minimum MTU in IPv6. This means the header overhead is almost
equal. More bits for addresses would require bigger headers and therefore more
overhead. Also, consider the maximum MTU on normal links (like Ethernet today):
it's 1500 octets (in special cases: 9k octets using Jumbo frames). Ultimately,
it wouldn't be a proper design if 10 % or 20 % of transported data in a Layer-
3 packet were used for addresses and not for payload.
Chapter 3. Address types
Table of Contents
1._Addresses_without_a_special_prefix
1.1._Localhost_address
1.2._Unspecified_address
1.3._IPv6_address_with_embedded_IPv4_address
2._Network_part,_also_known_as_prefix
2.1._Link_local_address_type
2.2._Site_local_address_type
2.3._Unique_Local_IPv6_Unicast_Addresses
2.4._Global_address_type_"(Aggregatable)_global_unicast"
2.5._Multicast_addresses
2.6._Anycast_addresses
3._Address_types_(host_part)
3.1._Automatically_computed_(also_known_as_stateless)
3.2._Manually_set
4._Prefix_lengths_for_routing
4.1._Prefix_lengths_(also_known_as_"netmasks")
4.2._Matching_a_route
Like IPv4, IPv6 addresses can be split into network and host parts using subnet
masks.
IPv4 has shown that sometimes it would be nice, if more than one IP address can
be assigned to an interface, each for a different purpose (aliases, multi-
cast). To remain extensible in the future, IPv6 is going further and allows
more than one IPv6 address to be assigned to an interface. There is currently
no limit defined by an RFC, only in the implementation of the IPv6 stack (to
prevent DoS attacks).
Using this large number of bits for addresses, IPv6 defines address types based
on some leading bits, which are hopefully never going to be broken in the
future (unlike IPv4 today and the history of class A, B, and C).
Also the number of bits are separated into a network part (upper 64 bits) and a
host part (lower 64 bits), to facilitate auto-configuration.
1. Addresses without a special prefix
1.1. Localhost address
This is a special address for the loopback interface, similiar to IPv4 with its
â€127.0.0.1â€. With IPv6, the localhost address is:
0000:0000:0000:0000:0000:0000:0000:0001
or compressed:
::1
Packets with this address as source or destination should never leave the
sending host.
1.2. Unspecified address
This is a special address like â€any†or â€0.0.0.0†in IPv4 . For IPv6 it's:
0000:0000:0000:0000:0000:0000:0000:0000
or:
::
These addresses are mostly used/seen in socket binding (to any IPv6 address) or
routing tables.
Note: the unspecified address cannot be used as destination address.
1.3. IPv6 address with embedded IPv4 address
There are two addresses which contain an IPv4 address.
1.3.1. IPv4-mapped IPv6 address
IPv4-only IPv6-compatible addresses are sometimes used/shown for sockets
created by an IPv6-enabled daemon, but only binding to an IPv4 address.
These addresses are defined with a special prefix of length 96 (a.b.c.d is the
IPv4 address):
0:0:0:0:0:ffff:a.b.c.d/96
or in compressed format
::ffff:a.b.c.d/96
For example, the IPv4 address 1.2.3.4 looks like this:
::ffff:1.2.3.4
1.3.2. IPv4-compatible IPv6 address
IPv4-compatible IPv6 addresses are used for automatic tunneling (RFC_2893_/
Transition_Mechanisms_for_IPv6_Hosts_and_Routers), which is being replaced by
6to4_tunneling.
0:0:0:0:0:0:a.b.c.d/96
or in compressed format
::a.b.c.d/96
2. Network part, also known as prefix
Designers defined some address types and left a lot of scope for future
definitions as currently unknown requirements arise. RFC_4291_/_IP_Version_6
Addressing_Architecture defines the current addressing scheme.
Now lets take a look at the different types of prefixes (and therefore address
types):
2.1. Link local address type
These are special addresses which will only be valid on a link of an interface.
Using this address as destination the packet would never pass through a router.
It's used for link communications such as:
* anyone else here on this link?
* anyone here with a special address (e.g. looking for a router)?
They begin with ( where â€x†is any hex character, normally â€0â€)
fe8x: <- currently the only one in use
fe9x:
feax:
febx:
An address with this prefix is found on each IPv6-enabled interface after
stateless auto-configuration (which is normally always the case).
2.2. Site local address type
These are addresses similar to the RFC_1918_/_Address_Allocation_for_Private
Internets in IPv4 today, with the added advantage that everyone who use this
address type has the capability to use the given 16 bits for a maximum number
of 65536 subnets. Comparable with the 10.0.0.0/8 in IPv4 today.
Another advantage: because it's possible to assign more than one address to an
interface with IPv6, you can also assign such a site local address in addition
to a global one.
It begins with:
fecx: <- most commonly used
fedx:
feex:
fefx:
(whereâ€x†is any hex character, normally â€0â€)
This address type is now deprecated RFC_3879_/_Deprecating_Site_Local
Addresses, but for a test in a lab, such addresses are still a good choice in
my humble opinion.
2.3. Unique Local IPv6 Unicast Addresses
Because the original defined site local addresses are not unique, this can lead
to major problems, if two former independend networks would be connected later
(overlapping of subnets). This and other issues lead to a new address type
named RFC_4193_/_Unique_Local_IPv6_Unicast_Addresses.
It begins with:
fcxx:
fdxx: <- currently the only one in use
A part of the prefix (40 bits) are generated using a pseudo-random algorithm
and it's improbable, that two generated ones are equal.
Example for a prefix (generated using a web-based tool: Goebel_Consult_/
createLULA):
fd0f:8b72:ac90::/48
2.4. Global address type "(Aggregatable) global unicast"
Today, there is one global address type defined (the first design, called
"provider based," was thrown away some years ago RFC_1884_/_IP_Version_6
Addressing_Architecture_[obsolete], you will find some remains in older Linux
kernel sources).
It begins with (x are hex characters)
2xxx:
3xxx:
Note: the prefix â€aggregatable†is thrown away in current drafts. There are
some further subtypes defined, see below:
2.4.1. 6bone test addresses
These were the first global addresses which were defined and in use. They all
start with
3ffe:
Example:
3ffe:ffff:100:f102::1
A special 6bone test address which will never be globally unique begins with
3ffe:ffff:
and is mostly shown in older examples. The reason for this is, if real
addresses are are shown, it's possible for someone to do a copy & paste to
their configuration files, thus inadvertently causing duplicates on a globally
unique address. This would cause serious problems for the original host (e.g.
getting answer packets for request that were never sent). Because IPv6 is now
in production, this prefix is no longer be delegated and is removed from
routing after 6.6.2006 (see RFC_3701_/_6bone_Phaseout for more).
2.4.2. 6to4 addresses
These addresses, designed for a special tunneling mechanism [RFC_3056_/
Connection_of_IPv6_Domains_via_IPv4_Clouds and RFC_2893_/_Transition_Mechanisms
for_IPv6_Hosts_and_Routers], encode a given IPv4 address and a possible subnet
and begin with
2002:
For example, representing 192.168.1.1/5:
2002:c0a8:0101:5::1
A small shell command line can help you generating such address out of a given
IPv4 one:
ipv4="1.2.3.4"; sla="5"; printf "2002:%02x%02x:%02x%02x:%04x::1" `echo $ipv4
¬ | tr "." " "` $sla
See also tunneling_using_6to4 and information_about_6to4_relay_routers.
2.4.3. Assigned by provider for hierarchical routing
These addresses are delegated to Internet service providers (ISP) and begin
currently with
2001:
Prefixes to major (backbone owning) ISPs (also known as LIRs) are delegated by
local_registries and currently have a prefix with length 32 assigned.
Any ISP customer can get a prefix with length 48.
2.4.4. Addresses reserved for examples and documentation
Currently, two address ranges are reserved for examples and documentation RFC
3849_/_IPv6_Address_Prefix_Reserved_for_Documentation:
3fff:ffff::/32
2001:0DB8::/32 EXAMPLENET-WF
These address ranges should be filtered based on source addresses and should
NOT be routed on border routers to the internet, if possible.
2.5. Multicast addresses
Multicast addresses are used for related services.
They alway start with (xx is the scope value)
ffxy:
They are split into scopes and types:
2.5.1. Multicast scopes
Multicast scope is a parameter to specify the maximum distance a multicast
packet can travel from the sending entity.
Currently, the following regions (scopes) are defined:
* ffx1: node-local, packets never leave the node.
* ffx2: link-local, packets are never forwarded by routers, so they never leave
the specified link.
* ffx5: site-local, packets never leave the site.
* ffx8: organization-local, packets never leave the organization (not so easy
to implement, must be covered by routing protocol).
* ffxe: global scope.
* others are reserved
2.5.2. Multicast types
There are many types already defined/reserved (see RFC_4291_/_IP_Version_6
Addressing_Architecture for details). Some examples are:
* All Nodes Address: ID = 1h, addresses all hosts on the local node (ff01:0:0:
0:0:0:0:1) or the connected link (ff02:0:0:0:0:0:0:1).
* All Routers Address: ID = 2h, addresses all routers on the local node (ff01:
0:0:0:0:0:0:2), on the connected link (ff02:0:0:0:0:0:0:2), or on the local
site (ff05:0:0:0:0:0:0:2)
2.5.3. Solicited node link-local multicast address
Special multicast address used as destination address in neighborhood
discovery, because unlike in IPv4, ARP no longer exists in IPv6.
An example of this address looks like
ff02::1:ff00:1234
Used prefix shows that this is a link-local multicast address. The suffix is
generated from the destination address. In this example, a packet should be
sent to address “fe80::1234â€, but the network stack doesn't know the current
layer 2 MAC address. It replaces the upper 104 bits with “ff02:0:0:0:0:1:ff00::
/104†and leaves the lower 24 bits untouched. This address is now used `on-
link' to find the corresponding node which has to send a reply containing its
layer 2 MAC address.
2.6. Anycast addresses
Anycast addresses are special addresses and are used to cover things like
nearest DNS server, nearest DHCP server, or similar dynamic groups. Addresses
are taken out of the unicast address space (aggregatable global or site-local
at the moment). The anycast mechanism (client view) will be handled by dynamic
routing protocols.
Note: Anycast addresses cannot be used as source addresses, they are only used
as destination addresses.
2.6.1. Subnet-router anycast address
A simple example for an anycast address is the subnet-router anycast address.
Assuming that a node has the following global assigned IPv6 address:
2001:db8:100:f101:210:a4ff:fee3:9566/64 <- Node's address
The subnet-router anycast address will be created blanking the suffix (least
significant 64 bits) completely:
2001:db8:100:f101::/64 <- subnet-router anycast address
3. Address types (host part)
For auto-configuration and mobility issues, it was decided to use the lower 64
bits as the host part of the address in most of the current address types.
Therefore each single subnet can hold a large amount of addresses.
This host part can be inspected differently:
3.1. Automatically computed (also known as stateless)
With auto-configuration, the host part of the address is computed by converting
the MAC address of an interface (if available), with the EUI-64 method, to a
unique IPv6 address. If no MAC address is available for this device (happens
e.g. on virtual devices), something else (like the IPv4 address or the MAC
address of a physical interface) is used instead.
E.g. a NIC has following MAC address (48 bit):
00:10:a4:01:23:45
This would be expanded according to theIEEE-Tutorial_EUI-64 design for EUI-48
identifiers to the 64 bit interface identifier:
0210:a4ff:fe01:2345
With a given prefix, the result is the IPv6 address shown in example above:
2001:0db8:0100:f101:0210:a4ff:fe01:2345
3.1.1. Privacy problem with automatically computed addresses and a solution
Because the "automatically computed" host part is globally unique (except when
a vendor of a NIC uses the same MAC address on more than one NIC), client
tracking is possible on the host when not using a proxy of any kind.
This is a known problem, and a solution was defined: privacy extension, defined
in RFC_3041_/_Privacy_Extensions_for_Stateless_Address_Autoconfiguration_in
IPv6 (there is also already a newer draft available: draft-ietf-ipv6-privacy-
addrs-v2-*). Using a random and a static value a new suffix is generated from
time to time. Note: this is only reasonable for outgoing client connections and
isn't really useful for well-known servers.
3.2. Manually set
For servers, it's probably easier to remember simpler addresses, this can also
be accommodated. It is possible to assign an additional IPv6 address to an
interface, e.g.
2001:0db8:100:f101::1
For manual suffixes like â€::1†shown in the above example, it's required that
the 7th most significant bit is set to 0 (the universal/local bit of the
automatically generated identifier). Also some other (otherwise unchosen ) bit
combinations are reserved for anycast addresses, too.
4. Prefix lengths for routing
In the early design phase it was planned to use a fully hierarchical routing
approach to reduce the size of the routing tables maximally. The reasons behind
this approach were the number of current IPv4 routing entries in core routers
(> 400 thousand in 2013), reducing the need of memory in hardware routers (ASIC
â€Application Specified Integrated Circuit†driven) to hold the routing table
and increase speed (fewer entries hopefully result in faster lookups).
Todays view is that routing will be mostly hierarchically designed for networks
with only one service provider. With more than one ISP connections, this is not
possible, and subject to an issue named multi-homing (infos on multi-homing:
drafts-ietf-multi6-*,IPv6_Multihoming_Solutions).
4.1. Prefix lengths (also known as "netmasks")
Similar to IPv4, the routable network path for routing to take place. Because
standard netmask notation for 128 bits doesn't look nice, designers employed
the IPv4 Classless Inter Domain Routing (CIDR, RFC_1519_/_Classless_Inter-
Domain_Routing) scheme, which specifies the number of bits of the IP address to
be used for routing. It is also called the "slash" notation.
An example:
2001:0db8:100:1:2:3:4:5/48
This notation will be expanded:
* Network:
2001:0db8:0100:0000:0000:0000:0000:0000
* Netmask:
ffff:ffff:ffff:0000:0000:0000:0000:0000
4.2. Matching a route
Under normal circumstances (no QoS), a lookup in a routing table results in the
route with the most significant number of address bits being selected. In other
words, the route with the biggest prefix length matches first.
For example if a routing table shows following entries (list is not complete):
2001:0db8:100::/48 :: U 1 0 0 sit1
2000::/3 ::192.88.99.1 UG 1 0 0 tun6to4
Shown destination addresses of IPv6 packets will be routed through shown device
2001:0db8:100:1:2:3:4:5/48 -> routed through device sit1
2001:0db8:200:1:2:3:4:5/48 -> routed through device tun6to4
Chapter 4. IPv6-ready system check
Table of Contents
1._IPv6-ready_kernel
1.1._Check_for_IPv6_support_in_the_current_running_kernel
1.2._Try_to_load_IPv6_module
1.3._Compile_kernel_with_IPv6_capabilities
1.4._IPv6-ready_network_devices
2._IPv6-ready_network_configuration_tools
2.1._net-tools_package
2.2._iproute_package
3._IPv6-ready_test/debug_programs
3.1._IPv6_ping
3.2._IPv6_traceroute6
3.3._IPv6_tracepath6
3.4._IPv6_tcpdump
4._IPv6-ready_programs
5._IPv6-ready_client_programs_(selection)
5.1._Checking_DNS_for_resolving_IPv6_addresses
5.2._IPv6-ready_telnet_clients
5.3._IPv6-ready_ssh_clients
5.4._IPv6-ready_web_browsers
6._IPv6-ready_server_programs
7._FAQ_(IPv6-ready_system_check)
7.1._Using_tools
Before you can start using IPv6 on a Linux host, you have to test, whether your
system is IPv6-ready. You may have to do some work to enable it first.
1. IPv6-ready kernel
Modern Linux distributions already contain IPv6-ready kernels, the IPv6
capability is generally compiled as a module, but it's possible that this
module is not loaded automatically on startup.
Note: you shouldn't anymore use kernel series 2.2.x, because it's not IPv6-up-
to-date anymore. Also the IPv6 support in series 2.4.x is no longer improved
according to definitions in latest RFCs. It's recommend to use series 2.6.x
now.
1.1. Check for IPv6 support in the current running kernel
To check, whether your current running kernel supports IPv6, take a look into
your /proc-file-system. Following entry must exists:
/proc/net/if_inet6
A short automatical test looks like:
# test -f /proc/net/if_inet6 && echo "Running kernel is IPv6 ready"
If this fails, it is quite likely, that the IPv6 module is not loaded.
1.2. Try to load IPv6 module
You can try to load the IPv6 module executing
# modprobe ipv6
If this is successful, this module should be listed, testable with following
auto-magically line:
# lsmod |grep -w 'ipv6' && echo "IPv6 module successfully loaded"
And the check shown above should now run successfully.
Note: unloading the module is currently not supported and can result, under
some circumstances, in a kernel crash.
1.2.1. Automatically loading of module
Its possible to automatically load the IPv6 module on demand. You only have to
add following line in the configuration file of the kernel module loader
(normally /etc/modules.conf or /etc/conf.modules):
alias net-pf-10 ipv6 # automatically load IPv6 module on demand
It's also possible to disable automatically loading of the IPv6 module using
following line
alias net-pf-10 off # disable automatically load of IPv6 module on demand
Additional note: in kernels series 2.6.x, the module loader mechanism was
changed. The new configuration file has to be named /etc/modprobe.conf instead
of /etc/modules.conf.
1.3. Compile kernel with IPv6 capabilities
If both above shown results were negative and your kernel has no IP6 support,
than you have the following options:
* Update your distribution to a current one which supports IPv6 out-of-the-box
(recommended for newbies)
* Compile a new vanilla kernel (easy, if you know which options you needed)
* Recompile kernel sources given by your Linux distribution (sometimes not so
easy)
* Compile a kernel with USAGI extensions
If you decide to compile a kernel, you should have previous experience in
kernel compiling and read the Linux_Kernel_HOWTO.
A comparison between vanilla and USAGI extended kernels is available on
IPv6+Linux-Status-Kernel.
1.3.1. Compiling a vanilla kernel
More detailed hints about compiling an IPv6-enabled kernel can be found e.g. on
IPv6-HOWTO-2#kernel.
Note: you should use whenever possible kernel series 2.6.x or above, because
the IPv6 support in series 2.4.x only will no longer get backported features
from 2.6.x and IPv6 support in series 2.2.x is hopeless outdated.
1.3.2. Compiling a kernel with USAGI extensions
Same as for vanilla kernel, only recommend for advanced users, which are
already familiar with IPv6 and kernel compilation. See also USAGI_project_/_FAQ
and Obtaining_the_best_IPv6_support_with_Linux_(Article) (Mirror).
1.4. IPv6-ready network devices
Not all existing network devices have already (or ever) the capability to
transport IPv6 packets. A current status can be found at IPv6+Linux-status-
kernel.html#transport.
A major issue is that because of the network layer structure of kernel
implementation an IPv6 packet isn't really recognized by it's IP header number
(6 instead of 4). It's recognized by the protocol number of the Layer 2
transport protocol. Therefore any transport protocol which doesn't use such
protocol number cannot dispatch IPv6 packets. Note: the packet is still
transported over the link, but on receivers side, the dispatching won't work
(you can see this e.g. using tcpdump).
1.4.1. Currently known never â€IPv6 capable linksâ€
* Serial Line IP (SLIP, RFC_1055_/_SLIP), should be better called now to
SLIPv4, device named: slX
* Parallel Line IP (PLIP), same like SLIP, device names: plipX
* ISDN with encapsulation rawip, device names: isdnX
1.4.2. Currently known â€not supported IPv6 capable linksâ€
* ISDN with encapsulation syncppp, device names: ipppX (design issue of the
ipppd, will be merged into more general PPP layer in kernel series 2.5.x)
2. IPv6-ready network configuration tools
You wont get very far, if you are running an IPv6-ready kernel, but have no
tools to configure IPv6. There are several packages in existence which can
configure IPv6.
2.1. net-tools package
The net-tool package includes some tools like ifconfig and route, which helps
you to configure IPv6 on an interface. Look at the output of ifconfig -? or
route -?, if something is shown like IPv6 or inet6, then the tool is IPv6-
ready.
Auto-magically check:
# /sbin/ifconfig -? 2>& 1|grep -qw 'inet6' && echo "utility
'ifconfig' is
¬ IPv6-ready"
Same check can be done for route:
# /sbin/route -? 2>& 1|grep -qw 'inet6' && echo "utility 'route'
is IPv6-ready"
2.2. iproute package
Alexey N. Kuznetsov (current a maintainer of the Linux networking code) created
a tool-set which configures networks through the netlink device. Using this
tool-set you have more functionality than net-tools provides, but its not very
well documented and isn't for the faint of heart.
# /sbin/ip 2>&1 |grep -qw 'inet6' && echo "utility 'ip' is IPv6-
ready"
If the program /sbin/ip isn't found, then I strongly recommend you install the
iproute package.
* You can get it from your Linux distribution (if contained)
* You're able to look for a proper RPM package at RPMfind/iproute (sometimes
rebuilding of a SRPMS package is recommended)
3. IPv6-ready test/debug programs
After you have prepared your system for IPv6, you now want to use IPv6 for
network communications. First you should learn how to examine IPv6 packets with
a sniffer program. This is strongly recommended because for debugging/
troubleshooting issues this can aide in providing a diagnosis very quickly.
3.1. IPv6 ping
This program is normally included in package iputils. It is designed for simple
transport tests sending ICMPv6 echo-request packets and wait for ICMPv6 echo-
reply packets.
Usage
# ping6 <hostwithipv6address>
# ping6 <ipv6address>
# ping6 [-I <device>] <link-local-ipv6address>
Some implementation also support %<device> suffix instead of using -I <device>,
e.g.
# ping6 <link-local-ipv6address>%<device>
Example
# ping6 -c 1 ::1
PING ::1(::1) from ::1 : 56 data bytes
64 bytes from ::1: icmp_seq=0 hops=64 time=292 usec
--- ::1 ping statistics ---
1 packets transmitted, 1 packets received, 0% packet loss
round-trip min/avg/max/mdev = 0.292/0.292/0.292/0.000 ms
Hint: ping6 needs raw access to socket and therefore root permissions. So if
non-root users cannot use ping6 then there are two possible problems:
1. ping6 is not in users path (probably, because ping6 is generally stored in
/usr/sbin -> add path (not really recommended)
2. ping6 doesn't execute properly, generally because of missing root
permissions -> chmod u+s /usr/sbin/ping6
3.1.1. Specifying interface for IPv6 ping
Using link-local addresses for an IPv6 ping, the kernel does not know through
which (physically or virtual) device it must send the packet - each device has
a link-local address. A try will result in following error message:
# ping6 fe80::212:34ff:fe12:3456
connect: Invalid argument
In this case you have to specify the interface additionally like shown here:
# ping6 -I eth0 -c 1 fe80::2e0:18ff:fe90:9205
PING fe80::212:23ff:fe12:3456(fe80::212:23ff:fe12:3456) from
¬ fe80::212:34ff:fe12:3478 eth0: 56 data bytes
64 bytes from fe80::212:23ff:fe12:3456: icmp_seq=0 hops=64 time=445 usec
--- fe80::2e0:18ff:fe90:9205 ping statistics ---
1 packets transmitted, 1 packets received, 0% packet loss round-trip
¬ min/avg/max/mdev = 0.445/0.445/0.445/0.000 ms
Example for %<device> notation:
# ping6 -c 1 fe80::2e0:18ff:fe90:9205%eth0
3.1.2. Ping6 to multicast addresses
An interesting mechanism to detect IPv6-active hosts on a link is to ping6 to
the link-local all-node multicast address:
# ping6 -I eth0 ff02::1
PING ff02::1(ff02::1) from fe80:::2ab:cdff:feef:0123 eth0: 56 data bytes
64 bytes from ::1: icmp_seq=1 ttl=64 time=0.104 ms
64 bytes from fe80::212:34ff:fe12:3450: icmp_seq=1 ttl=64 time=0.549 ms
(DUP!)
Example for %<device> notation:
# ping6 ff02::1%eth0
Unlike in IPv4, where replies to a ping on the broadcast address can be
disabled, in IPv6 currently this behavior cannot be disable except by local
IPv6 firewalling.
3.2. IPv6 traceroute6
3.2.1. IPv6 traceroute6 (old)
This older program is normally included in package iputils. It's a program
similar to IPv4 traceroute. Below you will see an example:
# traceroute6 www.6bone.net
traceroute to 6bone.net (3ffe:b00:c18:1::10) from 2001:0db8:0000:f101::2, 30
¬ hops max, 16 byte packets
1 localipv6gateway (2001:0db8:0000:f101::1) 1.354 ms 1.566 ms 0.407 ms
2 swi6T1-T0.ipv6.switch.ch (3ffe:2000:0:400::1) 90.431 ms 91.956 ms 92.377
ms
3 3ffe:2000:0:1::132 (3ffe:2000:0:1::132) 118.945 ms 107.982 ms 114.557 ms
4 3ffe:c00:8023:2b::2 (3ffe:c00:8023:2b::2) 968.468 ms 993.392 ms 973.441 ms
5 3ffe:2e00:e:c::3 (3ffe:2e00:e:c::3) 507.784 ms 505.549 ms 508.928 ms
6 www.6bone.net (3ffe:b00:c18:1::10) 1265.85 ms * 1304.74 ms
Note: unlike some modern versions of IPv4 traceroute, which can use ICMPv4
echo-request packets as well as UDP packets (default), current IPv6-traceroute
is only able to send UDP packets. As you perhaps already know, ICMP echo-
request packets are more accepted by firewalls or ACLs on routers inbetween
than UDP packets.
If a dedicated interface must be specified, this can be done by -i <device> or
using <address>%<device>.
3.2.2. traceroute since version 2
traceroute got native IPv6 support with version 2 and support all features as
for IPv4. Below you will see an example for an ICMP (ping) traceroute (root
permissions required)
# traceroute -I -n ipv6.google.com
traceroute to ipv6.google.com (2a00:1450:4016:804::200e), 30 hops max, 80
byte packets
1 2001:a61:*** 0.410 ms 0.510 ms 0.655 ms
2 2001:a60::89:705:1 26.428 ms 34.361 ms 41.777 ms
3 2001:a60::89:0:1:2 19.131 ms 19.163 ms 19.248 ms
4 2001:a60:0:106::2 20.464 ms 20.467 ms 20.457 ms
5 2001:4860::9:4000:cf86 21.836 ms * 21.852 ms
6 2001:4860:0:1::19 21.690 ms 21.585 ms 22.919 ms
7 2a00:1450:4016:804::200e 23.176 ms 19.310 ms 20.065 ms
If a dedicated interface must be specified, this can be done by -i <device>.
3.3. IPv6 tracepath6
This program is normally included in package iputils. It's a program like
traceroute6 and traces the path to a given destination discovering the MTU
along this path. Below you will see an example:
# tracepath6 www.6bone.net
1?: [LOCALHOST] pmtu 1480
1: 3ffe:401::2c0:33ff:fe02:14 150.705ms
2: 3ffe:b00:c18::5 267.864ms
3: 3ffe:b00:c18::5 asymm 2 266.145ms pmtu 1280
3: 3ffe:3900:5::2 asymm 4 346.632ms
4: 3ffe:28ff:ffff:4::3 asymm 5 365.965ms
5: 3ffe:1cff:0:ee::2 asymm 4 534.704ms
6: 3ffe:3800::1:1 asymm 4 578.126ms !N
Resume: pmtu 1280
3.4. IPv6 tcpdump
On Linux, tcpdump is the major tool for packet capturing. Below you find some
examples. IPv6 support is normally built-in in current releases of version 3.6.
tcpdump uses expressions for filtering packets to minimize the noise:
* icmp6: filters native ICMPv6 traffic
* ip6: filters native IPv6 traffic (including ICMPv6)
* proto ipv6: filters tunneled IPv6-in-IPv4 traffic
* not port ssh: to suppress displaying SSH packets for running tcpdump in a
remote SSH session
Also some command line options are very useful to catch and print more
information in a packet, mostly interesting for digging into ICMPv6 packets:
* “-s 512â€: increase the snap length during capturing of a packet to 512 bytes
* “-vvâ€: really verbose output
* “-nâ€: don't resolve addresses to names, useful if reverse DNS resolving isn't
working proper
3.4.1. IPv6 ping to 2001:0db8:100:f101::1 native over a local link
# tcpdump -t -n -i eth0 -s 512 -vv ip6 or proto ipv6
tcpdump: listening on eth0
2001:0db8:100:f101:2e0:18ff:fe90:9205 > 2001:0db8:100:f101::1: icmp6: echo
¬ request (len 64, hlim 64)
2001:0db8:100:f101::1 > 2001:0db8:100:f101:2e0:18ff:fe90:9205: icmp6: echo
¬ reply (len 64, hlim 64)
3.4.2. IPv6 ping to 2001:0db8:100::1 routed through an IPv6-in-IPv4-tunnel
1.2.3.4 and 5.6.7.8 are tunnel endpoints (all addresses are examples)
# tcpdump -t -n -i ppp0 -s 512 -vv ip6 or proto ipv6
tcpdump: listening on ppp0
1.2.3.4 > 5.6.7.8: 2002:ffff:f5f8::1 > 2001:0db8:100::1: icmp6: echo request
¬ (len 64, hlim 64) (DF) (ttl 64, id 0, len 124)
5.6.7.8 > 1.2.3.4: 2001:0db8:100::1 > 2002:ffff:f5f8::1: icmp6: echo reply
(len
¬ 64, hlim 61) (ttl 23, id 29887, len 124)
1.2.3.4 > 5.6.7.8: 2002:ffff:f5f8::1 > 2001:0db8:100::1: icmp6: echo request
¬ (len 64, hlim 64) (DF) (ttl 64, id 0, len 124)
5.6.7.8 > 1.2.3.4: 2001:0db8:100::1 > 2002:ffff:f5f8::1: icmp6: echo reply
(len
¬ 64, hlim 61) (ttl 23, id 29919, len 124)
4. IPv6-ready programs
Current distributions already contain the most needed IPv6 enabled client and
servers. See first on IPv6+Linux-Status-Distribution. If still not included,
you can check Current_Status_of_IPv6_Support_for_Networking_Applications
whether the program is already ported to IPv6 and usable with Linux. For common
used programs there are some hints available here later in this document.
5. IPv6-ready client programs (selection)
To run the following shown tests, it's required that your system is IPv6
enabled, and some examples show addresses which only can be reached if a
connection to the global IPv6 network is available.
Note: if using names instead of dedicated IPv4/IPv6 addresses which resolves to
IPv4 and IPv6 addresses, some command line clients support explicitly use of
specified protocol. Usually such clients have option â€-4†for IPv4 and â€-6†for
IPv6.
5.1. Checking DNS for resolving IPv6 addresses
Because of security updates in the last years every Domain Name System (DNS)
server should run newer software which already understands the (intermediate)
IPv6 address-type AAAA (the newer one named A6 isn't still common at the moment
because only supported using BIND9 and newer and also the non-existent support
of root domain IP6.ARPA). A simple test whether the used system can resolve
IPv6 addresses is
# host -t AAAA www.join.uni-muenster.de
and should show something like following:
www.join.uni-muenster.de. is an alias for tolot.join.uni-muenster.de.
tolot.join.uni-muenster.de. has AAAA address
¬ 2001:638:500:101:2e0:81ff:fe24:37c6
5.2. IPv6-ready telnet clients
IPv6-ready telnet clients are available. A simple test can be done with
$ telnet 3ffe:400:100::1 80
Trying 3ffe:400:100::1...
Connected to 3ffe:400:100::1.
Escape character is '^]'.
HEAD / HTTP/1.0
HTTP/1.1 200 OK
Date: Sun, 16 Dec 2001 16:07:21
GMT Server: Apache/2.0.28 (Unix)
Last-Modified: Wed, 01 Aug 2001 21:34:42 GMT
ETag: "3f02-a4d-b1b3e080"
Accept-Ranges: bytes
Content-Length: 2637
Connection: close
Content-Type: text/html; charset=ISO-8859-1
Connection closed by foreign host.
If the telnet client don't understand the IPv6 address and says something like
â€cannot resolve hostnameâ€, then it's not IPv6-enabled.
5.3. IPv6-ready ssh clients
5.3.1. openssh
Current versions of openssh are IPv6-ready. Depending on configuring before
compiling it has two behavior.
* --without-ipv4-default: the client tries an IPv6 connect first automatically
and fall back to IPv4 if not working
* --with-ipv4-default: default connection is IPv4, IPv6 connection must be
force like following example shows
$ ssh -6 ::1
user@::1's password: ******
[user@ipv6host user]$
If your ssh client doesn't understand the option â€-6†then it's not IPv6-
enabled, like most ssh version 1 packages.
5.3.2. ssh.com
SSH.com's SSH client and server is also IPv6 aware now and is free for all
Linux and FreeBSD machine regardless if used for personal or commercial use.
5.4. IPv6-ready web browsers
A current status of IPv6 enabled web browsers is available at Current_Status_of
IPv6_Support_for_Networking_Applications_-_HTTP.
Most of them have unresolved problems at the moment
1. If using an IPv4 only proxy in the settings, IPv6 requests will be sent to
the proxy, but the proxy will fail to understand the request and the
request fails. Solution: update proxy software (see later).
2. Automatic proxy settings (*.pac) cannot be extended to handle IPv6
requests differently (e.g. don't use proxy) because of their nature
(written in Java-script and well hard coded in source like to be seen in
Mozilla source code).
Also older versions don't understand an URL with IPv6 encoded addresses like
http://[2001:4dd0:f838:a006::6]/, IPv6 address of http://www.ipv6.bieringer.de/
(this given URLs only works with an IPv6-enabled browser!).
A short test is to try shown URL with a given browser and using no proxy.
5.4.1. URLs for testing
A good starting point for browsing using IPv6 is http://www.kame.net/. If the
turtle on this page is animated, the connection is via IPv6, otherwise the
turtle is static.
Other test servers are e.g.
* What_Is_My_IPv6
* ip.bieringer.de
* IPv6_Test
* test-ipv6.com
* The_ICSI_Netalyzr
* Speedtest_Comcast, IPv6_Speedtest_Comcast
6. IPv6-ready server programs
In this part of this HOWTO, more client specific issues are mentioned.
Therefore hints for IPv6-ready servers like sshd, httpd, telnetd, etc. are
shown below in Hints_for_IPv6-enabled_daemons.
7. FAQ (IPv6-ready system check)
7.1. Using tools
7.1.1. Q: Cannot ping6 to link-local addresses
Error message: "connect: Invalid argument"
Kernel doesn't know, which physical or virtual link you want to use to send
such ICMPv6 packets. Therefore it displays this error message.
Solution: Specify interface like: â€ping6 -I eth0 fe80::2e0:18ff:fe90:9205â€, see
also program_ping6_usage.
7.1.2. Q: Cannot ping6 or traceroute6 as normal user
Error message: â€icmp socket: Operation not permittedâ€
These utilities create special ICMPv6 packets and send them out. This is done
by using raw sockets in the kernel. But raw sockets can only be used by the
â€root†user. Therefore normal users get such error message.
Solution: If it's really needed that all users should be able to use these
utilities, you can add the â€suid†bit using â€chmod u+s /path/to/programâ€, see
also program_ping6_usage. If not all users should be able to, you can change
the group of the program to e.g. â€wheelâ€, add these power users to this group
and remove the execution bit for other users using â€chmod o-rwx /path/to/
programâ€. Or configure â€sudo†to enable your security policy.
Chapter 5. Configuring interfaces
Table of Contents
1._Different_network_devices
1.1._Physically_bounded
1.2._Virtually_bounded
2._Bringing_interfaces_up/down
2.1._Using_"ip"
2.2._Using_"ifconfig"
1. Different network devices
On a node, there exist different network devices. They can be collected in
classes
* Physically bounded, like eth0, tr0
* Virtually existing, like ppp0, tun0, tap0, sit0, isdn0, ippp0
1.1. Physically bounded
Physically bounded interfaces like Ethernet or Token-Ring are normal ones and
need no special treatment.
1.2. Virtually bounded
Virtually bounded interfaces always need special support
1.2.1. IPv6-in-IPv4 tunnel interfaces
These interfaces are normally named sitx. The name sit is a shortcut for Simple
Internet Transition. This device has the capability to encapsulate IPv6 packets
into IPv4 ones and tunnel them to a foreign endpoint.
sit0 has a special meaning and cannot be used for dedicated tunnels.
1.2.2. PPP interfaces
PPP interfaces get their IPv6 capability from an IPv6 enabled PPP daemon.
1.2.3. ISDN HDLC interfaces
IPv6 capability for HDLC with encapsulation ip is already built-in in the
kernel
1.2.4. ISDN PPP interfaces
ISDN PPP interfaces (ippp) aren't IPv6 enabled by kernel. Also there are also
no plans to do that because in kernel 2.5.+ they will be replaced by a more
generic ppp interface layer.
1.2.5. SLIP + PLIP
Like mentioned earlier, this interfaces don't support IPv6 transport (sending
is OK, but dispatching on receiving don't work).
1.2.6. Ether-tap device
Ether-tap devices are IPv6-enabled and also stateless configured. For use, the
module â€ethertap†has to be loaded before.
1.2.7. tun devices
Currently not tested by me.
1.2.8. ATM
01/2002: Aren't currently supported by vanilla kernel, supported by USAGI
extension
1.2.9. Others
Did I forget an interface?...
2. Bringing interfaces up/down
Two methods can be used to bring interfaces up or down.
2.1. Using "ip"
Usage:
# ip link set dev <interface> up
# ip link set dev <interface> down
Example:
# ip link set dev eth0 up
# ip link set dev eth0 down
2.2. Using "ifconfig"
Usage:
# /sbin/ifconfig <interface> up
# /sbin/ifconfig <interface> down
Example:
# /sbin/ifconfig eth0 up
# /sbin/ifconfig eth0 down
Chapter 6. Configuring IPv6 addresses
Table of Contents
1._Displaying_existing_IPv6_addresses
1.1._Using_"ip"
1.2._Using_"ifconfig"
2._Add_an_IPv6_address
2.1._Using_"ip"
2.2._Using_"ifconfig"
3._Removing_an_IPv6_address
3.1._Using_"ip"
3.2._Using_"ifconfig"
4._Automatic_IPv6_Address_Configuration
5._Enable_Privacy_Extension
5.1._Enable_Privacy_Extension_using_sysctl
5.2._Enable_Privacy_Extension_using_NetworkManager
5.3._Test_real_use_of_Privacy_Extension_IPv6_Addresses
There are different ways to configure an IPv6 address on an interface. You can
use use "ifconfig" or "ip".
1. Displaying existing IPv6 addresses
First you should check, whether and which IPv6 addresses are already configured
(perhaps auto-magically during stateless auto-configuration).
Just note that addresses beginning with â€fec0†are deprecated, but shown here
for completness!
1.1. Using "ip"
Usage:
# /sbin/ip -6 addr show dev <interface>
Example for a static configured host:
# /sbin/ip -6 addr show dev eth0
2: eth0: <BROADCAST,MULTICAST,UP&gt; mtu 1500 qdisc pfifo_ fast qlen 100
inet6 fe80::210:a4ff:fee3:9566/10 scope link
inet6 2001:0db8:0:f101::1/64 scope global
inet6 fec0:0:0:f101::1/64 scope site
Example for a host which is auto-configured
Here you see some auto-magically configured IPv6 addresses and their lifetime.
# /sbin/ip -6 addr show dev eth0
3: eth0: <BROADCAST,MULTICAST,PROMISC,UP&gt; mtu 1500 qdisc pfifo_fast
qlen
¬ 100
inet6 2002:d950:f5f8:f101:2e0:18ff:fe90:9205/64 scope global dynamic
valid_lft 16sec preferred_lft 6sec
inet6 3ffe:400:100:f101:2e0:18ff:fe90:9205/64 scope global dynamic
valid_lft 2591997sec preferred_lft 604797sec inet6 fe80::2e0:18ff:fe90:9205/
10
¬ scope link
1.2. Using "ifconfig"
Usage:
# /sbin/ifconfig <interface>
Example (output filtered with grep to display only IPv6 addresses). Here you
see different IPv6 addresses with different scopes.
# /sbin/ifconfig eth0 |grep "inet6 addr:"
inet6 addr: fe80::210:a4ff:fee3:9566/10 Scope:Link
inet6 addr: 2001:0db8:0:f101::1/64 Scope:Global
inet6 addr: fec0:0:0:f101::1/64 Scope:Site
2. Add an IPv6 address
Adding an IPv6 address is similar to the mechanism of "IP ALIAS" addresses in
Linux IPv4 addressed interfaces.
2.1. Using "ip"
Usage:
# /sbin/ip -6 addr add <ipv6address>/<prefixlength> dev <interface>
Example:
# /sbin/ip -6 addr add 2001:0db8:0:f101::1/64 dev eth0
2.2. Using "ifconfig"
Usage:
# /sbin/ifconfig <interface> inet6 add <ipv6address>/<prefixlength>
Example:
# /sbin/ifconfig eth0 inet6 add 2001:0db8:0:f101::1/64
3. Removing an IPv6 address
Not so often needed, be carefully with removing non existent IPv6 address,
sometimes using older kernels it results in a crash.
3.1. Using "ip"
Usage:
# /sbin/ip -6 addr del <ipv6address>/<prefixlength> dev <interface>
Example:
# /sbin/ip -6 addr del 2001:0db8:0:f101::1/64 dev eth0
3.2. Using "ifconfig"
Usage:
# /sbin/ifconfig <interface> inet6 del <ipv6address>/<prefixlength>
Example:
# /sbin/ifconfig eth0 inet6 del 2001:0db8:0:f101::1/64
4. Automatic IPv6 Address Configuration
In case, a Router Advertisement is received by a client, and IPv6
autoconfiguration is enabled (default on non-router), the client configures
itself an IPv6 address according to the prefix contained in the advertisement
(see also Section 4,_“Router_Advertisement_Daemon_(radvd)â€).
5. Enable Privacy Extension
Privacy Extension as described in RFC_4941_/_Privacy_Extensions_for_Stateless
Address_Autoconfiguration_in_IPv6 (obsoleted RFC_3041) is replacing the static
interface ID (mostly based on word-wide unique MAC address) used during
autoconfiguration by a pseudo-random one and generating from time to time a new
one deprecating the old one.
5.1. Enable Privacy Extension using sysctl
Temporary activation
Enable privacy extension for e.g. interface â€eth0†and prefer the generated
address:
# sysctl -w net.ipv6.conf.eth0.use_tempaddr=2
Afterwards, restart of the interface is necessary
# ip link set dev eth0 down
# ip link set dev eth0 up
Once a router advertisement is received, the result should look like following
# ip -6 addr show dev eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
inet6 2001:db8:0:1:8992:3c03:d6e2:ed72/64 scope global secondary dynamic
<- pseudo-random IID
valid_lft 604711sec preferred_lft 86311sec
inet6 2001:db8:0:1::224:21ff:fe01:2345/64 scope global <- IID based
on MAC
valid_lft 604711sec preferred_lft 86311sec
...
Permanent activation
For permanent activation, either a special initscript value per interface will
enable privacy or an entry in the /etc/sysctl.conf file like
net.ipv6.conf.eth0.use_tempaddr=2
Note: interface must already exists with proper name when sysctl.conf is
applied. If this is not the case (e.g. after reboot) one has to configure
privacy for all interfaces by default:
net.ipv6.conf.all.use_tempaddr=2
net.ipv6.conf.default.use_tempaddr=2
Changed/added values in /etc/sysctl.conf can be activated during runtime, but
at least an interface down/up or a reboot is recommended.
# sysctl -p
5.2. Enable Privacy Extension using NetworkManager
Modern (client) systems are using NetworkManager for configuring interfaces. A
command line tool is built-in which can be used to change settings which are
not available via GUI.
Examples based on version 0.9.9.1-5.git20140319.fc21
Check existing interfaces with:
# nmcli connection
NAME UUID TYPE DEVICE
ens4v1 d0fc2b2e-5fa0-4675-96b5-b723ca5c46db 802-3-ethernet ens4v1
Current amount of IPv6 privacy extension addresses can be checked with
# ip -o addr show dev ens4v1 | grep temporary | wc -l
0
Current IPv6 privacy extension settings can be checked with
# nmcli connection show ens4v1 |grep ip6-privacy
ipv6.ip6-privacy: -1 (unknown)
Enable IPv6 privacy extension and restart interface
# nmcli connection modify ens4v1 ipv6.ip6-privacy 2
# nmcli connection down ens4v1; nmcli connection up ens4v1
New IPv6 privacy extension settings can be checked with
# nmcli connection show ens4v1 |grep ip6-privacy
ipv6.ip6-privacy: 2 (active, prefer temporary IP)
Now IPv6 privacy extension addresses are configured on the interface
# ip -o addr show dev ens4v1 | grep temporary | wc -l
2
5.3. Test real use of Privacy Extension IPv6 Addresses
Whether the IPv6 address with an Interface ID generated by Privacy Extension is
really used for outgoing connections, one can browse to http://
ip.bieringer.de/, in case EUI64_SCOPE shows â€iid-privacyâ€, then everything is
working fine.
Chapter 7. Configuring normal IPv6 routes
Table of Contents
1._Displaying_existing_IPv6_routes
1.1._Using_"ip"
1.2._Using_"route"
2._Add_an_IPv6_route_through_a_gateway
2.1._Using_"ip"
2.2._Using_"route"
3._Removing_an_IPv6_route_through_a_gateway
3.1._Using_"ip"
3.2._Using_"route"
4._Add_an_IPv6_route_through_an_interface
4.1._Using_"ip"
4.2._Using_"route"
5._Removing_an_IPv6_route_through_an_interface
5.1._Using_"ip"
5.2._Using_"route"
6._FAQ_for_IPv6_routes
6.1._Support_of_an_IPv6_default_route
If you want to leave your link and want to send packets in the world wide IPv6-
Internet, you need routing. If there is already an IPv6 enabled router on your
link, it's possible enough to add IPv6 routes.
Just note that addresses beginning with â€fec0†are deprecated, but shown here
for completness!
1. Displaying existing IPv6 routes
First you should check, whether and which IPv6 addresses are already configured
(perhaps auto-magically during auto-configuration).
1.1. Using "ip"
Usage:
# /sbin/ip -6 route show [dev <device>]
Example:
# /sbin/ip -6 route show dev eth0
2001:0db8:0:f101::/64 proto kernel metric 256 mtu 1500 advmss 1440
fe80::/10 proto kernel metric 256 mtu 1500 advmss 1440
ff00::/8 proto kernel metric 256 mtu 1500 advmss 1440
default proto kernel metric 256 mtu 1500 advmss 1440
1.2. Using "route"
Usage:
# /sbin/route -A inet6
Example (output is filtered for interface eth0). Here you see different IPv6
routes for different addresses on a single interface.
# /sbin/route -A inet6 |grep -w "eth0"
2001:0db8:0:f101 ::/64 :: UA 256 0 0 eth0 <- Interface route for global
¬ address
fe80::/10 :: UA 256 0 0 eth0 <- Interface route for link-local
¬ address
ff00::/8 :: UA 256 0 0 eth0 <- Interface route for all
multicast
¬ addresses
::/0 :: UDA 256 0 0 eth0 <- Automatic default route
2. Add an IPv6 route through a gateway
Mostly needed to reach the outside with IPv6 using an IPv6-enabled router on
your link.
2.1. Using "ip"
Usage:
# /sbin/ip -6 route add <ipv6network>/<prefixlength> via <ipv6address>
¬ [dev <device>]
Example:
# /sbin/ip -6 route add default via 2001:0db8:0:f101::1
2.2. Using "route"
Usage:
# /sbin/route -A inet6 add <ipv6network>/<prefixlength> gw
¬ <ipv6address> [dev <device>]
A device can be needed, too, if the IPv6 address of the gateway is a link local
one.
Following shown example adds a default route through gateway 2001:0db8:0:f101::
1
# /sbin/route -A inet6 add default gw 2001:0db8:0:f101::1
3. Removing an IPv6 route through a gateway
Not so often needed manually, mostly done by network configure scripts on
shutdown (full or per interface)
3.1. Using "ip"
Usage:
# /sbin/ip -6 route del <ipv6network>/<prefixlength> via <ipv6address>
¬ [dev <device>]
Example:
# /sbin/ip -6 route del default via 2001:0db8:0:f101::1
3.2. Using "route"
Usage:
# /sbin/route -A inet6 del <network>/<prefixlength> gw <ipv6address> [dev
¬ <device>]
Example for removing upper added route again:
# /sbin/route -A inet6 del default gw 2001:0db8:0:f101::1
4. Add an IPv6 route through an interface
Not often needed, sometimes in cases of dedicated point-to-point links.
4.1. Using "ip"
Usage:
# /sbin/ip -6 route add <ipv6network>/<prefixlength> dev <device>
¬ metric 1
Example:
# /sbin/ip -6 route add default dev eth0 metric 1
Metric â€1†is used here to be compatible with the metric used by route, because
the default metric on using â€ip†is â€1024â€.
4.2. Using "route"
Usage:
# /sbin/route -A inet6 add <ipv6network>/<prefixlength> dev <device>
Example:
# /sbin/route -A inet6 add default dev eth0
5. Removing an IPv6 route through an interface
Not so often needed to use by hand, configuration scripts will use such on
shutdown.
5.1. Using "ip"
Usage:
# /sbin/ip -6 route del <ipv6network>/<prefixlength> dev <device>
Example:
# /sbin/ip -6 route del default dev eth0
5.2. Using "route"
Usage:
# /sbin/route -A inet6 del <network>/<prefixlength> dev <device>
Example:
# /sbin/route -A inet6 del default dev eth0
6. FAQ for IPv6 routes
6.1. Support of an IPv6 default route
One idea of IPv6 was a hierachical routing, therefore only less routing entries
are needed in routers.
There are some issues in current Linux kernels:
6.1.1. Clients (not routing any packet!)
Client can setup a default route like prefix â€::/0â€, they also learn such route
on autoconfiguration e.g. using radvd on the link like following example shows:
# ip -6 route show | grep ^default
default via fe80::212:34ff:fe12:3450 dev eth0 proto kernel metric 1024
expires
¬ 29sec mtu 1500 advmss 1440
6.1.2. Routers in case of packet forwarding
Older Linux kernel (at least <= 2.4.17) don't support default routes. You can
set them up, but the route lookup fails when a packet should be forwarded
(normal intention of a router). If you're still using such older kernel,
â€default routing†can be setup using the currently used global address prefix
â€2000::/3â€.
Note: take care about default routing without address filtering on edge
routers. Otherwise unwanted multicast or site-local traffic can leave the edge.
Chapter 8. Neighbor Discovery
Table of Contents
1._Displaying_neighbors_using_â€ipâ€
2._Manipulating_neighbors_table_using_â€ipâ€
2.1._Manually_add_an_entry
2.2._Manually_delete_an_entry
2.3._More_advanced_settings
Neighbor discovery was the IPv6 successor for the ARP (Address Resolution
Protocol) in IPv4. You can retrieve information about the current neighbors, in
addition you can set and delete entries. The kernel keeps tracking of
successful neighbor detection (like ARP in IPv4). You can dig into the learnt
table using â€ipâ€.
1. Displaying neighbors using â€ipâ€
With following command you can display the learnt or configured IPv6 neighbors
# ip -6 neigh show [dev <device>]
The following example shows one neighbor, which is a reachable router
# ip -6 neigh show
fe80::201:23ff:fe45:6789 dev eth0 lladdr 00:01:23:45:67:89 router nud
reachable
2. Manipulating neighbors table using â€ipâ€
2.1. Manually add an entry
With following command you are able to manually add an entry
# ip -6 neigh add <IPv6 address> lladdr <link-layer address> dev <device>
Example:
# ip -6 neigh add fec0::1 lladdr 02:01:02:03:04:05 dev eth0
2.2. Manually delete an entry
Like adding also an entry can be deleted:
# ip -6 neigh del <IPv6 address> lladdr <link-layer address> dev <device>
Example:
# ip -6 neigh del fec0::1 lladdr 02:01:02:03:04:05 dev eth0
2.3. More advanced settings
The tool â€ip†is less documentated, but very strong. See online â€help†for
more:
# ip -6 neigh help
Usage: ip neigh { add | del | change | replace } { ADDR [ lladdr LLADDR ]
[ nud { permanent | noarp | stale | reachable } ]
| proxy ADDR } [ dev DEV ]
ip neigh {show|flush} [ to PREFIX ] [ dev DEV ] [ nud STATE ]
Looks like some options are only for IPv4...if you can contribute information
about flags and advanced usage, pls. send.
Chapter 9. Configuring IPv6-in-IPv4 tunnels
Table of Contents
1._Types_of_tunnels
1.1._Static_point-to-point_tunneling
1.2._Automatically_tunneling
1.3._6to4-Tunneling
1.4._UDP_encapsulated_IPv6_tunneling
2._Displaying_existing_tunnels
2.1._Using_"ip"
2.2._Using_"route"
3._Setup_of_point-to-point_tunnel
3.1._Add_point-to-point_tunnels
3.2._Removing_point-to-point_tunnels
3.3._Numbered_point-to-point_tunnels
4._Setup_of_6to4_tunnels
4.1._Add_a_6to4_tunnel
4.2._Remove_a_6to4_tunnel
If you want to leave your link and you have no IPv6 capable network around you,
you need IPv6-in-IPv4 tunneling to reach the world wide IPv6-Internet.
There are some kind of tunnel mechanism and also some possibilities to setup
tunnels.
1. Types of tunnels
There are more than one possibility to tunnel IPv6 packets over IPv4-only
links.
1.1. Static point-to-point tunneling
A point-to-point tunnel is a dedicated tunnel to an endpoint, which knows about
your IPv6 network (for backward routing) and the IPv4 address of your tunnel
endpoint and defined in RFC_4213_/_Basic_Transition_Mechanisms_for_IPv6_Hosts
and_Routers. Requirements:
* IPv4 address of your local tunnel endpoint must be static, global unique and
reachable from the foreign tunnel endpoint
o If no static IPv4 address is available, the tunnel provider must support
authentication of the dynamic IPv4 address, like SixXS_/_AICCU (3740/udp)
or gogo6 (3653/udp).
* A global IPv6 prefix assigned to you
o It is also possible that additional IPv6 networks are routed through this
tunnel.
* A foreign tunnel endpoint which is capable to route your IPv6 prefix to your
local tunnel endpoint (mostly remote manual configuration required)
Tunnel provider for static point-to-point tunneling:
* Hurricane_Electric
* SixXS
1.2. Automatically tunneling
Automatic tunneling occurs, when a node directly connects another node gotten
the IPv4 address of the other node before.
1.3. 6to4-Tunneling
6to4 tunneling (RFC_3056_/_Connection_of_IPv6_Domains_via_IPv4_Clouds) uses a
simple mechanism to create automatic tunnels. Each node with a global unique
IPv4 address is able to be a 6to4 tunnel endpoint (if no IPv4 firewall
prohibits traffic). 6to4 tunneling is mostly not a one-to-one tunnel. This case
of tunneling can be divided into upstream and downstream tunneling. Also, a
special IPv6 address indicates that this node will use 6to4 tunneling for
connecting the world-wide IPv6 network
1.3.1. Generation of 6to4 prefix
The 6to4 address is defined like following (schema is taken from RFC_3056_/
Connection_of_IPv6_Domains_via_IPv4_Clouds):
| 3+13 | 32 | 16 | 64 bits |
+---+------+-----------+--------+--------------------------------+
| FP+TLA | V4ADDR | SLA ID | Interface ID |
| 0x2002 | | | |
+---+------+-----------+--------+--------------------------------+
FP and TLA together (16 bits) have the value 0x2002. V4ADDR is the node's
global unique IPv4 address (in hexadecimal notation). SLA is the subnet
identifier (65536 local subnets possible) and are usable to represent your
local network structure.
For gateways, such prefix is generated by normally using SLA â€0000†and suffix
â€::1†(not a must, can be an arbitrary one with local-scope) and assigned to
the 6to4 tunnel interface. Note that Microsoft Windows uses V4ADDR also for
suffix.
1.3.2. 6to4 upstream tunneling
The node has to know to which foreign tunnel endpoint its in IPv4 packed IPv6
packets should be send to. In â€early†days of 6to4 tunneling, dedicated
upstream accepting routers were defined. See NSayer's_6to4_information for a
list of routers.
Nowadays, 6to4 upstream routers can be found auto-magically using the anycast
address 192.88.99.1. In the background routing protocols handle this, see RFC
3068_/_An_Anycast_Prefix_for_6to4_Relay_Routers for details.
1.3.3. 6to4 downstream tunneling
The downstream (IPv6 backbone -> your 6to4 enabled node) is not really fix and
can vary from foreign host which originated packets were send to. There exist
two possibilities:
* Foreign host uses 6to4 and sends packet direct back to your node (see below)
* Foreign host sends packets back to the world-wide IPv6 network and depending
on the dynamic routing a relay router of an ISP which announces 2002::/16 via
BGP will create a automatic tunnel back to your node.
1.3.4. Possible 6to4 traffic
* from 6to4 to 6to4: is normally directly tunneled between the both 6to4
enabled hosts
* from 6to4 to non-6to4: is sent via upstream tunneling
* non-6to4 to 6to4: is sent via downstream tunneling
Note, that because of possible asymmetric routing problems with a broken 6to4
relay can be hard to troubleshoot.
1.4. UDP encapsulated IPv6 tunneling
UDP encapsulated IPv6 tunneling is usally used if no global IPv4 address is
available on the internal endpoint, but using Network Adress Translation (NAT)
it can still reach related endpoints using UDP ports described below.
1.4.1. Teredo Tunnel
RFC_4380_/_Teredo:_Tunneling_IPv6_over_UDP_through_Network_Address
Translationsdescribes tunneling of IPv6 packets via IPv4 UDP bubbles, see also
Wikipedia_/_Teredo. It uses usually 3544/udp. Linux client is named miredo and
usable out-of-the-box. This tunnel method can only connect a single client to
the global IPv6 network..
1.4.2. AYIYA Tunnel
Tunnel provider SixXS has also IPv6-in-UDP-in-IPv4 (5072/udp) capability, for
using it, the AYIYA mode must be enabled.
1.4.3. gogo6 Tunnel
Tunnel provider gogo6 has also IPv6-in-UDP-in-IPv4 (3653/udp) capability, for
using it, the v6udpv4 mode must be enabled.
2. Displaying existing tunnels
2.1. Using "ip"
Usage:
# /sbin/ip -6 tunnel show [<device>]
Example:
# /sbin/ip -6 tunnel show
sit0: ipv6/ip remote any local any ttl 64 nopmtudisc
sit1: ipv6/ip remote 195.226.187.50 local any ttl 64
2.2. Using "route"
Usage:
# /sbin/route -A inet6
Example (output is filtered to display only tunnels through virtual interface
sit0):
# /sbin/route -A inet6 | grep "\Wsit0\W*$"
::/96 :: U 256 2 0 sit0
2002::/16 :: UA 256 0 0 sit0
2000::/3 ::193.113.58.75 UG 1 0 0 sit0
fe80::/10 :: UA 256 0 0 sit0
ff00::/8 :: UA 256 0 0 sit0
3. Setup of point-to-point tunnel
There are 3 possibilities to add or remove point-to-point tunnels.
A good additional information about tunnel setup using â€ip†is Configuring
tunnels_with_iproute2_(article) (Mirror).
Note: support of such kind of tunnels is provided by kernel module â€sitâ€
(potentially not possible on Virtuozzo platforms)
3.1. Add point-to-point tunnels
3.1.1. Using "ip"
Common method at the moment for a small amount of tunnels.
Usage for creating a tunnel device (but it's not up afterward, also a TTL must
be specified because the default value is 0).
# /sbin/ip tunnel add <device> mode sit ttl <ttldefault> remote
¬ <ipv4addressofforeigntunnel> local <ipv4addresslocal>
Usage (generic example for three tunnels):
# /sbin/ip tunnel add sit1 mode sit ttl <ttldefault> remote
¬ <ipv4addressofforeigntunnel1> local <ipv4addresslocal>
# /sbin/ip link set dev sit1 up
# /sbin/ip -6 route add <prefixtoroute1> dev sit1 metric 1
# /sbin/ip tunnel add sit2 mode sit ttl <ttldefault>
¬ <ipv4addressofforeigntunnel2> local <ipv4addresslocal>
# /sbin/ip link set dev sit2 up
# /sbin/ip -6 route add <prefixtoroute2> dev sit2 metric 1
# /sbin/ip tunnel add sit3 mode sit ttl <ttldefault>
¬ <ipv4addressofforeigntunnel3> local <ipv4addresslocal>
# /sbin/ip link set dev sit3 up
# /sbin/ip -6 route add <prefixtoroute3> dev sit3 metric 1
3.1.2. Using "ifconfig" and "route" (deprecated)
This not very recommended way to add a tunnel because it's a little bit
strange. No problem if adding only one, but if you setup more than one, you
cannot easy shutdown the first ones and leave the others running.
Usage (generic example for three tunnels):
# /sbin/ifconfig sit0 up
# /sbin/ifconfig sit0 tunnel <ipv4addressofforeigntunnel1>
# /sbin/ifconfig sit1 up
# /sbin/route -A inet6 add <prefixtoroute1> dev sit1
# /sbin/ifconfig sit0 tunnel <ipv4addressofforeigntunnel2>
# /sbin/ifconfig sit2 up
# /sbin/route -A inet6 add <prefixtoroute2> dev sit2
# /sbin/ifconfig sit0 tunnel <ipv4addressofforeigntunnel3>
# /sbin/ifconfig sit3 up
# /sbin/route -A inet6 add <prefixtoroute3> dev sit3
Important: DON'T USE THIS, because this setup implicit enable "automatic
tunneling" from anywhere in the Internet, this is a risk, and it should not be
advocated.
3.1.3. Using "route" only
It's also possible to setup tunnels in Non Broadcast Multiple Access (NBMA)
style, it's a easy way to add many tunnels at once. But none of the tunnel can
be numbered (which is a not required feature).
Usage (generic example for three tunnels):
# /sbin/ifconfig sit0 up
# /sbin/route -A inet6 add <prefixtoroute1> gw
¬ ::<ipv4addressofforeigntunnel1> dev sit0
# /sbin/route -A inet6 add <prefixtoroute2> gw
¬ ::<ipv4addressofforeigntunnel2> dev sit0
# /sbin/route -A inet6 add <prefixtoroute3> gw
¬ ::<ipv4addressofforeigntunnel3> dev sit0
Important: DON'T USE THIS, because this setup implicit enable "automatic
tunneling" from anywhere in the Internet, this is a risk, and it should not be
advocated.
3.2. Removing point-to-point tunnels
Manually not so often needed, but used by scripts for clean shutdown or restart
of IPv6 configuration.
3.2.1. Using "ip"
Usage for removing a tunnel device:
# /sbin/ip tunnel del <device>
Usage (generic example for three tunnels):
# /sbin/ip -6 route del <prefixtoroute1> dev sit1
# /sbin/ip link set sit1 down
# /sbin/ip tunnel del sit1
# /sbin/ip -6 route del <prefixtoroute2> dev sit2
# /sbin/ip link set sit2 down
# /sbin/ip tunnel del sit2
# /sbin/ip -6 route del <prefixtoroute3> dev sit3
# /sbin/ip link set sit3 down
# /sbin/ip tunnel del sit3
3.2.2. Using "ifconfig" and "route" (deprecated because not very funny)
Not only the creation is strange, the shutdown also...you have to remove the
tunnels in backorder, means the latest created must be removed first.
Usage (generic example for three tunnels):
# /sbin/route -A inet6 del <prefixtoroute3> dev sit3
# /sbin/ifconfig sit3 down
# /sbin/route -A inet6 del <prefixtoroute2> dev sit2
# /sbin/ifconfig sit2 down
# /sbin/route -A inet6 add <prefixtoroute1> dev sit1
# /sbin/ifconfig sit1 down
# /sbin/ifconfig sit0 down
3.2.3. Using "route"
This is like removing normal IPv6 routes.
Usage (generic example for three tunnels):
# /sbin/route -A inet6 del <prefixtoroute1> gw
¬ ::<ipv4addressofforeigntunnel1> dev sit0
# /sbin/route -A inet6 del <prefixtoroute2> gw
¬ ::<ipv4addressofforeigntunnel2> dev sit0
# /sbin/route -A inet6 del <prefixtoroute3> gw
¬ ::<ipv4addressofforeigntunnel3> dev sit0
# /sbin/ifconfig sit0 down
3.3. Numbered point-to-point tunnels
Sometimes it's needed to configure a point-to-point tunnel with IPv6 addresses
like in IPv4 today. This is only possible with the first (ifconfig+route -
deprecated) and third (ip+route) tunnel setup. In such cases, you can add the
IPv6 address to the tunnel interface like shown on interface configuration.
4. Setup of 6to4 tunnels
Pay attention that the support of 6to4 tunnels currently lacks on vanilla
kernel series 2.2.x (see systemcheck/kernel for more information). Also note
that that the prefix length for a 6to4 address is 16 because of from network
point of view, all other 6to4 enabled hosts are on the same layer 2.
4.1. Add a 6to4 tunnel
First, you have to calculate your 6to4 prefix using your local assigned global
routable IPv4 address (if your host has no global routable IPv4 address, in
special cases NAT on border gateways is possible):
Assuming your IPv4 address is
1.2.3.4
the generated 6to4 prefix will be
2002:0102:0304::
Local 6to4 gateways should (but it's not a must, you can choose an arbitrary
suffix with local-scope, if you feel better) always assigned the suffix â€::1â€,
therefore your local 6to4 address will be
2002:0102:0304::1
Use e.g. following for automatic generation:
ipv4="1.2.3.4"; printf "2002:%02x%02x:%02x%02x::1" `echo $ipv4 | tr "." " "`
There are two ways possible to setup 6to4 tunneling now.
4.1.1. Using "ip" and a dedicated tunnel device
This is now the recommended way (a TTL must be specified because the default
value is 0).
Create a new tunnel device
# /sbin/ip tunnel add tun6to4 mode sit ttl <ttldefault> remote any local
¬ <localipv4address>
Bring interface up
# /sbin/ip link set dev tun6to4 up
Add local 6to4 address to interface (note: prefix length 16 is important!)
# /sbin/ip -6 addr add <local6to4address>/16 dev tun6to4
Add (default) route to the global IPv6 network using the all-6to4-routers IPv4
anycast address
# /sbin/ip -6 route add default via ::192.88.99.1 dev tun6to4 metric 1
It was reported that some versions of â€ip†(e.g. SuSE Linux 9.0) don't support
IPv4-compatible IPv6 addresses for gateways, in this case the related IPv6
address has to be used:
# /sbin/ip -6 route add default via 2002:c058:6301::1 dev tun6to4 metric 1
4.1.2. Using "ifconfig" and "route" and generic tunnel device â€sit0â€
(deprecated)
This is now deprecated because using the generic tunnel device sit0 doesn't let
specify filtering per device.
Bring generic tunnel interface sit0 up
# /sbin/ifconfig sit0 up
Add local 6to4 address to interface
# /sbin/ifconfig sit0 add <local6to4address>/16
Add (default) route to the global IPv6 network using the all-6to4-relays IPv4
anycast address
# /sbin/route -A inet6 add default gw ::192.88.99.1 dev sit0
4.2. Remove a 6to4 tunnel
4.2.1. Using "ip" and a dedicated tunnel device
Remove all routes through this dedicated tunnel device
# /sbin/ip -6 route flush dev tun6to4
Shut down interface
# /sbin/ip link set dev tun6to4 down
Remove created tunnel device
# /sbin/ip tunnel del tun6to4
4.2.2. Using â€ifconfig†and â€route†and generic tunnel device â€sit0â€
(deprecated)
Remove (default) route through the 6to4 tunnel interface
# /sbin/route -A inet6 del default gw ::192.88.99.1 dev sit0
Remove local 6to4 address to interface
# /sbin/ifconfig sit0 del <local6to4address>/16
Shut down generic tunnel device (take care about this, perhaps it's still in
use...)
# /sbin/ifconfig sit0 down
Chapter 10. Configuring IPv4-in-IPv6 tunnels
Table of Contents
1._Displaying_existing_tunnels
2._Setup_of_point-to-point_tunnel
3._Removing_point-to-point_tunnels
RFC_2473_/_Generic_Packet_Tunneling_in_IPv6_Specification specifies mechanisms
to tunnel several different packet types over IPv6 including IPv4.
NOTE: Support for IPv4-in-IPv6 tunnel is available only since kernel version
2.6.22.
1. Displaying existing tunnels
Usage:
# /sbin/ip -6 tunnel show [<device>]
Example:
# /sbin/ip -6 tunnel show mode any
ip6tnl0: ipv6/ipv6 remote :: local :: encaplimit 0 hoplimit 0 tclass 0x00
¬ flowlabel 0x00000 (flowinfo 0x00000000)
ip6tnl1: ip/ipv6 remote fd00:0:0:2::a local fd00:0:0:2::1 dev eth1 encaplimit
4
¬ hoplimit 64 tclass 0x00 flowlabel 0x00000 (flowinfo 0x00000000)
NOTE: If you don't include "mode any", only IPv6-in-IPv6 tunnels are displayed.
2. Setup of point-to-point tunnel
Usage for creating a 4over6 tunnel device (but it's not up afterward)
# /sbin/ip tunnel add <device> mode ip4ip6 remote
<ipv6addressofforeigntunnel>
¬ local <ipv6addresslocal>
Usage (generic example for three tunnels):
# /sbin/ip -6 tunnel add ip6tnl1 mode ip4ip6 remote
¬ <ipv6addressofforeigntunnel1> local <ipv6addresslocal>
# /sbin/ip link set dev ip6tnl1 up
# /sbin/ip -6 route add <prefixtoroute1> dev ip6tnl1 metric 1
# /sbin/ip -6 tunnel add ip6tnl2 mode ip4ip6 remote
¬ <ipv6addressofforeigntunnel2> local <ipv6addresslocal>
# /sbin/ip link set dev ip6tnl2 up
# /sbin/ip -6 route add <prefixtoroute2> dev ip6tnl2 metric 1
# /sbin/ip -6 tunnel add ip6tnl3 mode ip4ip6 remote
¬ <ipv6addressofforeigntunnel3> local <ipv6addresslocal>
# /sbin/ip link set dev ip6tnl3 up
# /sbin/ip -6 route add <prefixtoroute3> dev ip6tnl3 metric 1
3. Removing point-to-point tunnels
Usage for removing a tunnel device:
# /sbin/ip -6 tunnel del <device>
Usage (generic example for three tunnels):
# /sbin/ip -6 route del <prefixtoroute1> dev ip6tnl1
# /sbin/ip link set ip6tnl1 down
# /sbin/ip -6 tunnel del ip6tnl1
# /sbin/ip -6 route del <prefixtoroute2> dev ip6tnl2
# /sbin/ip link set ip6tnl2 down
# /sbin/ip -6 tunnel del ip6tnl2
# /sbin/ip -6 route del <prefixtoroute3> dev ip6tnl3
# /sbin/ip link set ip6tnl3 down
# /sbin/ip -6 tunnel del ip6tnl3
Chapter 11. Kernel settings in /proc-filesystem
Table of Contents
1._How_to_access_the_/proc-filesystem
1.1._Using_â€catâ€_and_â€echoâ€
1.2._Using_â€sysctlâ€
1.3._Values_found_in_/proc-filesystems
2._Entries_in_/proc/sys/net/ipv6/
2.1._conf/default/*
2.2._conf/all/*
2.3._conf/interface/*
2.4._neigh/default/*
2.5._neigh/interface/*
2.6._route/*
3._IPv6-related_entries_in_/proc/sys/net/ipv4/
3.1._ip_*
3.2._tcp_*
3.3._icmp_*
3.4._others
4._IPv6-related_entries_in_/proc/net/
4.1._if_inet6
4.2._ipv6_route
4.3._sockstat6
4.4._tcp6
4.5._udp6
4.6._igmp6
4.7._raw6
4.8._ip6_flowlabel
4.9._rt6_stats
4.10._snmp6
4.11._ip6_tables_names
Note: the source of this section is mostly the file â€ip-sysctl.txt†which is
included in current kernel sources in directory â€Documentation/networkingâ€.
Credits to Pekka Savola for maintaining the IPv6-related part in this file.
Also some text is more or less copied & pasted into this document.
1. How to access the /proc-filesystem
1.1. Using â€cat†and â€echoâ€
Using â€cat†and â€echo†is the simplest way to access the /proc filesystem, but
some requirements are needed for that
* The /proc-filesystem had to be enabled in kernel, means on compiling
following switch has to be set
CONFIG_PROC_FS=y
* The /proc-filesystem was mounted before, which can be tested using
# mount | grep "type proc"
none on /proc type proc (rw)
* You need read and sometimes also write access (normally root only) to the /
proc-filesystem
Normally, only entries in /proc/sys/* are writable, the others are readonly and
for information retrieving only.
1.1.1. Retrieving a value
The value of an entry can be retrieved using â€catâ€:
# cat /proc/sys/net/ipv6/conf/all/forwarding
0
1.1.2. Setting a value
A new value can be set (if entry is writable) using â€echoâ€:
# echo "1" >/proc/sys/net/ipv6/conf/all/forwarding
1.2. Using â€sysctlâ€
Using the â€sysctl†program to access the kernel switches is a modern method
today. You can use it also, if the /proc-filesystem isn't mounted. But you have
only access to /proc/sys/*!
The program â€sysctl†is included in package â€procps†(on Red Hat Linux
systems).
* The sysctl-interface had to be enabled in kernel, means on compiling
following switch has to be set
CONFIG_SYSCTL=y
1.2.1. Retrieving a value
The value of an entry can be retrieved now:
# sysctl net.ipv6.conf.all.forwarding
net.ipv6.conf.all.forwarding = 0
1.2.2. Setting a value
A new value can be set (if entry is writable):
# sysctl -w net.ipv6.conf.all.forwarding=1
net.ipv6.conf.all.forwarding = 1
Note: Don't use spaces around the â€=†on setting values. Also on multiple
values per line, quote them like e.g.
# sysctl -w net.ipv4.ip_local_port_range="32768 61000"
net.ipv4.ip_local_port_range = 32768 61000
1.2.3. Additionals
Note: There are sysctl versions in the wild which displaying â€/†instead of the
â€.â€
For more details take a look into sysctl's manpage.
Hint: for digging fast into the settings, use the option â€-a†(display all
entries) in conjunction with â€grepâ€.
1.3. Values found in /proc-filesystems
There are several formats seen in /proc-filesystem:
* BOOLEAN: simple a â€0†(false) or a â€1†(true)
* INTEGER: an integer value, can be unsigned, too
* more sophisticated lines with several values: sometimes a header line is
displayed also, if not, have a look into the kernel source to retrieve
information about the meaning of each value...
2. Entries in /proc/sys/net/ipv6/
2.1. conf/default/*
Change the interface-specific default settings.
2.2. conf/all/*
Change all the interface-specific settings.
Exception: â€conf/all/forwarding†has a different meaning here
2.2.1. conf/all/forwarding
* Type: BOOLEAN
This enables global IPv6 forwarding between all interfaces.
In IPv6 you can't control forwarding per device, forwarding control has to be
done using IPv6-netfilter (controlled with ip6tables) rulesets and specify
input and output devices (see Firewalling/Netfilter6 for more). This is
different to IPv4, where you are able to control forwarding per device
(decision is made on interface where packet came in).
This also sets all interfaces' Host/Router setting 'forwarding' to the
specified value. See below for details. This referred to as global forwarding.
If this value is 0, no IPv6 forwarding is enabled, packets never leave another
interface, neither physical nor logical like e.g. tunnels.
2.3. conf/interface/*
Change special settings per interface.
The functional behaviour for certain settings is different depending on whether
local forwarding is enabled or not.
2.3.1. accept_ra
* Type: BOOLEAN
* Functional default: enabled if local forwarding is disabled. disabled if
local forwarding is enabled.
Accept Router Advertisements, and autoconfigure this interface with received
data.
2.3.2. accept_redirects
* Type: BOOLEAN
* Functional default: enabled if local forwarding is disabled. disabled if
local forwarding is enabled.
Accept Redirects sent by an IPv6 router.
2.3.3. autoconf
* Type: BOOLEAN
* Functional default: enabled if accept_ra_pinfo is enabled. disabled if
accept_ra_pinfo is disabled.
Autoconfigure addresses using prefix information from router advertisements.
2.3.4. dad_transmits
* Type: INTEGER
* Default: 1
The amount of Duplicate Address Detection probes to send.
2.3.5. forwarding
* Type: BOOLEAN
* Default: FALSE if global forwarding is disabled (default), otherwise TRUE
Configure interface-specific Host/Router behaviour.
Note: It is recommended to have the same setting on all interfaces; mixed
router/host scenarios are rather uncommon.
* Value FALSE: By default, Host behaviour is assumed. This means:
1. IsRouter flag is not set in Neighbour Advertisements.
2. Router Solicitations are being sent when necessary.
3. If accept_ra is TRUE (default), accept Router Advertisements (and do
autoconfiguration).
4. If accept_redirects is TRUE (default), accept Redirects.
* Value TRUE: If local forwarding is enabled, Router behaviour is assumed. This
means exactly the reverse from the above:
1. IsRouter flag is set in Neighbour Advertisements.
2. Router Solicitations are not sent.
3. Router Advertisements are ignored.
4. Redirects are ignored.
2.3.6. hop_limit
* Type: INTEGER
* Default: 64
Default Hop Limit to set.
2.3.7. mtu
* Type: INTEGER
* Default: 1280 (IPv6 required minimum)
Default Maximum Transfer Unit
2.3.8. router_solicitation_delay
* Type: INTEGER
* Default: 1
Number of seconds to wait after interface is brought up before sending Router
Solicitations.
2.3.9. router_solicitation_interval
* Type: INTEGER
* Default: 4
Number of seconds to wait between Router Solicitations.
2.3.10. router_solicitations
* Type: INTEGER
* Default: 3
Number of Router Solicitations to send until assuming no routers are present.
2.4. neigh/default/*
Change default settings for neighbor detection and some special global interval
and threshold values:
2.4.1. gc_thresh1
* Type: INTEGER
* Default: 128
More to be filled.
2.4.2. gc_thresh2
* Type: INTEGER
* Default: 512
More to be filled.
2.4.3. gc_thresh3
* Type: INTEGER
* Default: 1024
Tuning parameter for neighbour table size.
Increase this value if you have a lot of interfaces and problem with routes
start to act mysteriously and fail. Or if a running Zebra_(routing_daemon)
reports:
ZEBRA: netlink-listen error: No buffer space available, type=RTM_NEWROUTE
(24),
¬ seq=426, pid=0
2.4.4. gc_interval
* Type: INTEGER
* Default: 30
More to be filled.
2.5. neigh/interface/*
Change special settings per interface for neighbor detection.
2.5.1. anycast_delay
* Type: INTEGER
* Default: 100
More to be filled.
2.5.2. gc_stale_time
* Type: INTEGER
* Default: 60
More to be filled.
2.5.3. proxy_qlen
* Type: INTEGER
* Default: 64
More to be filled.
2.5.4. unres_qlen
* Type: INTEGER
* Default: 3
More to be filled.
2.5.5. app_solicit
* Type: INTEGER
* Default: 0
More to be filled.
2.5.6. locktime
* Type: INTEGER
* Default: 0
More to be filled.
2.5.7. retrans_time
* Type: INTEGER
* Default: 100
More to be filled.
2.5.8. base_reachable_time
* Type: INTEGER
* Default: 30
More to be filled.
2.5.9. mcast_solicit
* Type: INTEGER
* Default: 3
More to be filled.
2.5.10. ucast_solicit
* Type: INTEGER
* Default: 3
More to be filled
2.5.11. delay_first_probe_time
* Type: INTEGER
* Default: 5
More to be filled.
2.5.12. proxy_delay
* Type: INTEGER
* Default: 80
More to be filled.
2.6. route/*
Change global settings for routing.
2.6.1. flush
Removed in newer kernel releases - more to be filled.
2.6.2. gc_interval
* Type: INTEGER
* Default: 30
More to be filled.
2.6.3. gc_thresh
* Type: INTEGER
* Default: 1024
More to be filled.
2.6.4. mtu_expires
* Type: INTEGER
* Default: 600
More to be filled.
2.6.5. gc_elasticity
* Type: INTEGER
* Default: 0
More to be filled.
2.6.6. gc_min_interval
* Type: INTEGER
* Default: 5
More to be filled.
2.6.7. gc_timeout
* Type: INTEGER
* Default: 60
More to be filled.
2.6.8. min_adv_mss
* Type: INTEGER
* Default: 12
More to be filled.
2.6.9. max_size
* Type: INTEGER
* Default: 4096
More to be filled.
3. IPv6-related entries in /proc/sys/net/ipv4/
At the moment (and this will be until IPv4 is completly converted to an
independend kernel module) some switches are also used here for IPv6.
3.1. ip_*
3.1.1. ip_local_port_range
This control setting is used by IPv6 also.
3.2. tcp_*
This control settings are used by IPv6 also.
3.3. icmp_*
This control settings are not used by IPv6. To enable ICMPv6 rate limiting
(which is very recommended because of the capability of ICMPv6 storms)
netfilter-v6 rules must be used.
3.4. others
Unknown, but probably not used by IPv6.
4. IPv6-related entries in /proc/net/
In /proc/net there are several read-only entries available. You cannot retrieve
information using â€sysctl†here, so use e.g. â€catâ€.
4.1. if_inet6
* Type: One line per addresss containing multiple values
Here all configured IPv6 addresses are shown in a special format. The example
displays for loopback interface only. The meaning is shown below (see â€net/
ipv6/addrconf.c†for more).
# cat /proc/net/if_inet6
00000000000000000000000000000001 01 80 10 80 lo
+------------------------------+ ++ ++ ++ ++ ++
| | | | | |
1 2 3 4 5 6
1. IPv6 address displayed in 32 hexadecimal chars without colons as separator
2. Netlink device number (interface index) in hexadecimal (see â€ip addr†,
too)
3. Prefix length in hexadecimal
4. Scope value (see kernel source †include/net/ipv6.h†and â€net/ipv6/
addrconf.c†for more)
5. Interface flags (see â€include/linux/rtnetlink.h†and â€net/ipv6/addrconf.câ€
for more)
6. Device name
4.2. ipv6_route
* Type: One line per route containing multiple values
Here all configured IPv6 routes are shown in a special format. The example
displays for loopback interface only. The meaning is shown below (see â€net/
ipv6/route.c†for more).
# cat /proc/net/ipv6_route
00000000000000000000000000000000 00 00000000000000000000000000000000 00
+------------------------------+ ++ +------------------------------+ ++
| | | |
1 2 3 4
¬ 00000000000000000000000000000000 ffffffff 00000001 00000001 00200200 lo
¬ +------------------------------+ +------+ +------+ +------+ +------+ ++
¬ | | | | | |
¬ 5 6 7 8 9 10
1. IPv6 destination network displayed in 32 hexadecimal chars without colons
as separator
2. IPv6 destination prefix length in hexadecimal
3. IPv6 source network displayed in 32 hexadecimal chars without colons as
separator
4. IPv6 source prefix length in hexadecimal
5. IPv6 next hop displayed in 32 hexadecimal chars without colons as
separator
6. Metric in hexadecimal
7. Reference counter
8. Use counter
9. Flags
10. Device name
4.3. sockstat6
* Type: One line per protocol with description and value
Statistics about used IPv6 sockets. Example:
# cat /proc/net/sockstat6
TCP6: inuse 7
UDP6: inuse 2
RAW6: inuse 1
FRAG6: inuse 0 memory 0
4.4. tcp6
To be filled.
4.5. udp6
To be filled.
4.6. igmp6
To be filled.
4.7. raw6
To be filled.
4.8. ip6_flowlabel
To be filled.
4.9. rt6_stats
To be filled.
4.10. snmp6
* Type: One line per SNMP description and value
SNMP statistics, can be retrieved via SNMP server and related MIB table by
network management software.
4.11. ip6_tables_names
Available netfilter6 tables
Chapter 12. Netlink-Interface to kernel
To be filled...I have no experience with that...
Chapter 13. Address Resolver & Selection
Additional info can be found at
* Linux_&_IPv6:_getaddrinfo_and_search_domains_-_Research
* RFC_3484_on_Linux
* Karl Auer's Blog: Controlling_IPv6_source_address_selection , IPv6_Source
Address_Selection_-_what,_why,_how
* Into6: /etc/gai.conf_-_it_ain't_what_you_think_it_is
Address Resolver & Destination Address Selection
Name to IPv4 or IPv6 address resolving is usually done using a libc resolver
library. Usually the function getaddrinfo is used for that. In case of more
than one IPv6 address is returned, according to RFC_3484_/_Default_Address
Selection_for_Internet_Protocol_version_6 a sorting should be applied, which
can be optionally configured.
The â€magic†is controlled by a file named /etc/gai.conf (it can be that it is
empty or missing by default). Default is usually somewhere stored in
documentation, see â€man gai.conf†or e.g. /usr/share/doc/glibc-common/gai.conf.
For controlling sort order by configuration following are needed for testing:
* A host in DNS returning more than one IPv6 address, e.g.
$ dig +short aaaa st1.bieringer.de
2001:4dd0:ff00:834::2
2a01:238:423d:8800:85b3:9e6b:3019:8909
* Lookup via DNS (/etc/hosts won't work)
* /etc/gai.conf with proper config, e.g.
precedence ::1/128 50 # default
precedence ::/0 40 # default
precedence 2002::/16 30 # default
precedence ::/96 20 # default
precedence ::ffff:0:0/96 10 # default
precedence 2001:4dd0:ff00:834::/64 80 # dst-A
precedence 2a01:238:423d:8800::/64 90 # dst-B
* For tests use e.g. telnet client
$ telnet st1.bieringer.de
Trying 2a01:238:423d:8800:85b3:9e6b:3019:8909... (dst-B)
...
Trying 2001:4dd0:ff00:834::2... (dst-A)
...
* If precedence is changed in configuration
precedence 2001:4dd0:ff00:834::/64 90 # dst-A ex 80
precedence 2a01:238:423d:8800::/64 80 # dst-B ex 90
* The order is changed accordingly
$ telnet st1.bieringer.de
Trying 2001:4dd0:ff00:834::2... (dst-A)
...
Trying 2a01:238:423d:8800:85b3:9e6b:3019:8909... (dst-B)
...
Source Address Selection
Source address selection in Linux is done automatically by kernel and usually
only using information from routing tables and try to match the same scope of
address.
Source Address Selection with â€ip addrlabelâ€
With extension of internal â€ip addrlabel†a source address can be bound to a
destination address (e.g. selected via mechanisms above). Binding means here:
â€same label†(label is a number).
* Default of â€ip addrlabel†(here on CentOS 6):
# ip addrlabel
prefix ::1/128 label 0
prefix ::/96 label 3
prefix ::ffff:0.0.0.0/96 label 4
prefix 2001::/32 label 6
prefix 2001:10::/28 label 7
prefix 2002::/16 label 2
prefix fc00::/7 label 5
prefix ::/0 label 1
* System is multihomed (here on one interface), router provides 2 prefixes via
radvd:
# ip -6 addr show dev eth1 | grep -w inet6 |grep -w global
inet6 2001:6f8:12d8:2:5054:ff:fefb:6582/64 scope global dynamic
inet6 2001:6f8:900:8cbc:5054:ff:fefb:6582/64 scope global dynamic
* Connect now to server (shown above)
$ telnet st1.bieringer.de
Trying 2001:4dd0:ff00:834::2... (dst-A)
...
Trying 2a01:238:423d:8800:85b3:9e6b:3019:8909... (dst-B)
...
* Related tcpdump with filter â€tcp and dst port 23†shows only the use of the
upper local source IPv6 address
IP6 2001:6f8:12d8:2:5054:ff:fefb:6582.37762 > 2001:4dd0:ff00:834::2.telnet:
(src-A -> dst-A)
IP6 2001:6f8:12d8:2:5054:ff:fefb:6582.45754 > 2a01:238:423d:8800:85b3:9e6b:
3019:8909.telnet: (src-A -> dst-B)
* Binding now source and destination with â€ip addrlabelâ€
# ip addrlabel add prefix 2001:6f8:12d8:2::/64 label 200
# ip addrlabel add prefix 2001:6f8:900:8cbc::/64 label 300
# ip addrlabel add prefix 2001:4dd0:ff00:834::/64 label 200
# ip addrlabel add prefix 2a01:238:423d:8800::/64 label 300
* Resulting â€ip addrlabelâ€
# ip addrlabel
prefix ::1/128 label 0
prefix ::/96 label 3
prefix ::ffff:0.0.0.0/96 label 4
prefix 2a01:238:423d:8800::/64 label 300 # dst-B
prefix 2001:4dd0:ff00:834::/64 label 200 # dst-A
prefix 2001:6f8:900:8cbc::/64 label 300 # src-B
prefix 2001:6f8:12d8:2::/64 label 200 # src-A
prefix 2001::/32 label 6
prefix 2001:10::/28 label 7
prefix 2002::/16 label 2
prefix fc00::/7 label 5
prefix ::/0 label 1
* Connect now to server again
$ telnet st1.bieringer.de
Trying 2001:4dd0:ff00:834::2... (dst-A)
...
Trying 2a01:238:423d:8800:85b3:9e6b:3019:8909... (dst-B)
...
* Related tcpdump with filter â€tcp and dst port 23†shows now the use of both
local source IPv6 addresses according to the configured pairs A and B
IP6 2001:6f8:12d8:2:5054:ff:fefb:6582.37765 > 2001:4dd0:ff00:834::2.telnet:
(src-A -> dst-A)
IP6 2001:6f8:900:8cbc:5054:ff:fefb:6582.39632 > 2a01:238:423d:8800:85b3:9e6b:
3019:8909.telnet: (src-B -> dst-B)
Setup of persistent â€ip addrtable†is probably currently not supported by Linux
distributions, so extension of network init scripts or rc.local must be used
for that. A script which uses information from /etc/gai.conf and configure â€ip
addrtable†accordingly can be found here: /etc/gai.conf_-_it_ain't_what_you
think_it_is
Chapter 14. Network debugging
Table of Contents
1._Server_socket_binding
1.1._Using_â€netstatâ€_for_server_socket_binding_check
2._Examples_for_tcpdump_packet_dumps
2.1._Router_discovery
2.2._Neighbor_discovery
1. Server socket binding
1.1. Using â€netstat†for server socket binding check
It's always interesting which server sockets are currently active on a node.
Using â€netstat†is a short way to get such information:
Used options: -nlptu
Example:
# netstat -nlptu
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
¬ PID/Program name
tcp 0 0 0.0.0.0:32768 0.0.0.0:* LISTEN
¬ 1258/rpc.statd
tcp 0 0 0.0.0.0:32769 0.0.0.0:* LISTEN
¬ 1502/rpc.mountd
tcp 0 0 0.0.0.0:515 0.0.0.0:* LISTEN
¬ 22433/lpd Waiting
tcp 0 0 1.2.3.1:139 0.0.0.0:* LISTEN
¬ 1746/smbd
tcp 0 0 0.0.0.0:111 0.0.0.0:* LISTEN
¬ 1230/portmap
tcp 0 0 0.0.0.0:6000 0.0.0.0:* LISTEN
¬ 3551/X
tcp 0 0 1.2.3.1:8081 0.0.0.0:* LISTEN
¬ 18735/junkbuster
tcp 0 0 1.2.3.1:3128 0.0.0.0:* LISTEN
¬ 18822/(squid)
tcp 0 0 127.0.0.1:953 0.0.0.0:* LISTEN
¬ 30734/named
tcp 0 0 ::ffff:1.2.3.1:993 :::* LISTEN
¬ 6742/xinetd-ipv6
tcp 0 0 :::13 :::* LISTEN
¬ 6742/xinetd-ipv6
tcp 0 0 ::ffff:1.2.3.1:143 :::* LISTEN
¬ 6742/xinetd-ipv6
tcp 0 0 :::53 :::* LISTEN
¬ 30734/named
tcp 0 0 :::22 :::* LISTEN
¬ 1410/sshd
tcp 0 0 :::6010 :::* LISTEN
¬ 13237/sshd
udp 0 0 0.0.0.0:32768 0.0.0.0:
*
¬ 1258/rpc.statd
udp 0 0 0.0.0.0:2049 0.0.0.0:
*
¬ -
udp 0 0 0.0.0.0:32770 0.0.0.0:
*
¬ 1502/rpc.mountd
udp 0 0 0.0.0.0:32771 0.0.0.0:
*
¬ -
udp 0 0 1.2.3.1:137 0.0.0.0:
*
¬ 1751/nmbd
udp 0 0 0.0.0.0:137 0.0.0.0:
*
¬ 1751/nmbd
udp 0 0 1.2.3.1:138 0.0.0.0:
*
¬ 1751/nmbd
udp 0 0 0.0.0.0:138 0.0.0.0:
*
¬ 1751/nmbd
udp 0 0 0.0.0.0:33044 0.0.0.0:
*
¬ 30734/named
udp 0 0 1.2.3.1:53 0.0.0.0:
*
¬ 30734/named
udp 0 0 127.0.0.1:53 0.0.0.0:
*
¬ 30734/named
udp 0 0 0.0.0.0:67 0.0.0.0:
*
¬ 1530/dhcpd
udp 0 0 0.0.0.0:67 0.0.0.0:
*
¬ 1530/dhcpd
udp 0 0 0.0.0.0:32858 0.0.0.0:
*
¬ 18822/(squid)
udp 0 0 0.0.0.0:4827 0.0.0.0:
*
¬ 18822/(squid)
udp 0 0 0.0.0.0:111 0.0.0.0:
*
¬ 1230/portmap
udp 0 0 :::53 :::
*
¬ 30734/named
2. Examples for tcpdump packet dumps
Here some examples of captured packets are shown, perhaps useful for your own
debugging...
...more coming next...
2.1. Router discovery
2.1.1. Router advertisement
15:43:49.484751 fe80::212:34ff:fe12:3450 > ff02::1: icmp6: router
¬ advertisement(chlim=64, router_ltime=30, reachable_time=0,
¬ retrans_time=0)(prefix info: AR valid_ltime=30, preffered_ltime=20,
¬ prefix=2002:0102:0304:1::/64)(prefix info: LAR valid_ltime=2592000,
¬ preffered_ltime=604800, prefix=2001:0db8:0:1::/64)(src lladdr:
¬ 0:12:34:12:34:50) (len 88, hlim 255)
Router with link-local address â€fe80::212:34ff:fe12:3450†send an advertisement
to the all-node-on-link multicast address â€ff02::1†containing two prefixes
â€2002:0102:0304:1::/64†(lifetime 30 s) and â€2001:0db8:0:1::/64†(lifetime
2592000 s) including its own layer 2 MAC address â€0:12:34:12:34:50â€.
2.1.2. Router solicitation
15:44:21.152646 fe80::212:34ff:fe12:3456 > ff02::2: icmp6: router
solicitation
¬ (src lladdr: 0:12:34:12:34:56) (len 16, hlim 255)
Node with link-local address â€fe80::212:34ff:fe12:3456†and layer 2 MAC address
â€0:12:34:12:34:56†is looking for a router on-link, therefore sending this
solicitation to the all-router-on-link multicast address â€ff02::2â€.
2.2. Neighbor discovery
2.2.1. Neighbor discovery solicitation for duplicate address detection
Following packets are sent by a node with layer 2 MAC address â€0:12:34:12:34:
56†during autoconfiguration to check whether a potential address is already
used by another node on the link sending this to the solicited-node link-local
multicast address.
* Node wants to configure its link-local address â€fe80::212:34ff:fe12:3456â€,
checks for duplicate now
15:44:17.712338 :: > ff02::1:ff12:3456: icmp6: neighbor sol: who has
¬ fe80::212:34ff:fe12:3456(src lladdr: 0:12:34:12:34:56) (len 32, hlim 255)
* Node wants to configure its global address â€2002:0102:0304:1:212:34ff:fe12:
3456†(after receiving advertisement shown above), checks for duplicate now
15:44:21.905596 :: > ff02::1:ff12:3456: icmp6: neighbor sol: who has
¬ 2002:0102:0304:1:212:34ff:fe12:3456(src lladdr: 0:12:34:12:34:56) (len 32,
¬ hlim 255)
* Node wants to configure its global address â€2001:0db8:0:1:212:34ff:fe12:3456â€
(after receiving advertisement shown above), checks for duplicate now
15:44:22.304028 :: > ff02::1:ff12:3456: icmp6: neighbor sol: who has
¬ 2001:0db8:0:1:212:34ff:fe12:3456(src lladdr: 0:12:34:12:34:56) (len 32,
hlim
¬ 255)
2.2.2. Neighbor discovery solicitation for looking for host or gateway
* Node wants to send packages to â€2001:0db8:0:1::10†but has no layer 2 MAC
address to send packet, so send solicitation now
13:07:47.664538 2002:0102:0304:1:2e0:18ff:fe90:9205 > ff02::1:ff00:10: icmp6:
¬ neighbor sol: who has 2001:0db8:0:1::10(src lladdr: 0:e0:18:90:92:5) (len
32,
¬ hlim 255)
* Node looks for â€fe80::10†now
13:11:20.870070 fe80::2e0:18ff:fe90:9205 > ff02::1:ff00:10: icmp6: neighbor
¬ sol: who has fe80::10(src lladdr: 0:e0:18:90:92:5) (len 32, hlim 255)
Chapter 15. Support for persistent IPv6 configuration in Linux distributions
Table of Contents
1._Red_Hat_Linux_and_â€clonesâ€
1.1._Test_for_IPv6_support_of_network_configuration_scripts
1.2._Short_hint_for_enabling_IPv6_on_current_RHL_7.1,_7.2,_7.3,_...
2._SuSE_Linux
2.1._SuSE_Linux_7.3
2.2._SuSE_Linux_8.0
2.3._SuSE_Linux_8.1
3._Debian_Linux
3.1._Further_information
Some Linux distribution contain already support of a persistent IPv6
configuration using existing or new configuration and script files and some
hook in the IPv4 script files.
1. Red Hat Linux and â€clonesâ€
Since starting writing the IPv6_&_Linux_-_HowTo it was my intention to
enable a persistent IPv6 configuration which catch most of the wished cases
like host-only, router-only, dual-homed-host, router with second stub network,
normal tunnels, 6to4 tunnels, and so on. Nowadays there exists a set of
configuration and script files which do the job very well (never heard about
real problems, but I don't know how many use the set). Because this
configuration and script files are extended from time to time, they got their
own homepage: initscripts-ipv6_homepage (Mirror). Because I began my IPv6
experience using a Red Hat Linux 5.0 clone, my IPv6 development systems are
mostly Red Hat Linux based now, it's kind a logic that the scripts are
developed for this kind of distribution (so called historic issue). Also it was
very easy to extend some configuration files, create new ones and create some
simple hook for calling IPv6 setup during IPv4 setup.
Fortunately, in Red Hat Linux since 7.1 a snapshot of my IPv6 scripts is
included, this was and is still further on assisted by Pekka Savola.
Mandrake since version 8.0 also includes an IPv6-enabled initscript package,
but a minor bug still prevents usage (â€ifconfig†misses â€inet6†before â€addâ€).
1.1. Test for IPv6 support of network configuration scripts
You can test, whether your Linux distribution contain support for persistent
IPv6 configuration using my set. Following script library should exist:
/etc/sysconfig/network-scripts/network-functions-ipv6
Auto-magically test:
# test -f /etc/sysconfig/network-scripts/network-functions-ipv6 &&
echo "Main
¬ IPv6 script library exists"
The version of the library is important if you miss some features. You can get
it executing following (or easier look at the top of the file):
# source /etc/sysconfig/network-scripts/network-functions-ipv6 &&
¬ getversion_ipv6_functions
20011124
In shown example, the used version is 20011124. Check this against latest
information on initscripts-ipv6_homepage (Mirror) to see what has been changed.
You will find there also a change-log.
1.2. Short hint for enabling IPv6 on current RHL 7.1, 7.2, 7.3, ...
* Check whether running system has already IPv6 module loaded
# modprobe -c | grep net-pf-10
alias net-pf-10 off
* If result is â€offâ€, then enable IPv6 networking by editing /etc/sysconfig/
network, add following new line
NETWORKING_IPV6=yes
* Reboot or restart networking using
# service network restart
* Now IPv6 module should be loaded
# modprobe -c | grep ipv6
alias net-pf-10 ipv6
If your system is on a link which provides router advertisement,
autoconfiguration will be done automatically. For more information which
settings are supported see /usr/share/doc/initscripts-$version/sysconfig.txt.
2. SuSE Linux
In newer 7.x versions there is a really rudimentary support available, see /
etc/rc.config for details.
Because of the really different configuration and script file structure it is
hard (or impossible) to use the set for Red Hat Linux and clones with this
distribution. In versions 8.x they completly change their configuration setup.
2.1. SuSE Linux 7.3
* How_to_setup_6to4_IPv6_with_SuSE_7.3
2.2. SuSE Linux 8.0
2.2.1. IPv6 address configuration
Edit file /etc/sysconfig/network/ifcfg-<Interface-Name> and setup following
value
IP6ADDR="<ipv6-address>/<prefix>"
2.2.2. Additional information
See file /usr/share/doc/packages/sysconfig/README
2.3. SuSE Linux 8.1
2.3.1. IPv6 address configuration
Edit file /etc/sysconfig/network/ifcfg-<Interface-Name> and setup following
value
IPADDR="<ipv6-address>/<prefix>"
2.3.2. Additional information
See file /usr/share/doc/packages/sysconfig/Network
3. Debian Linux
Following information was contributed by Stephane Bortzmeyer <bortzmeyer at nic
dot fr>
1. Be sure that IPv6 is loaded, either because it is compiled into the kernel
or because the module is loaded. For the latest, three solutions, adding
it to /etc/modules, using the pre-up trick shown later or using kmod (not
detailed here).
2. Configure your interface. Here we assume eth0 and address (2001:0db8:1234:
5::1:1). Edit /etc/network/interfaces:
iface eth0 inet6 static
pre-up modprobe ipv6
address 2001:0db8:1234:5::1:1
# To suppress completely autoconfiguration:
# up echo 0 > /proc/sys/net/ipv6/conf/all/autoconf
netmask 64
# The router is autoconfigured and has no fixed address.
# It is magically
# found. (/proc/sys/net/ipv6/conf/all/accept_ra). Otherwise:
#gateway 2001:0db8:1234:5::1
And you reboot or you just
# ifup --force eth0
and you have your static address.
3.1. Further information
* IPv6_with_Debian_Linux
* Jean-Marc V. Liotier's HOWTO_for_Freenet6_&_Debian_Users (announced
24.12.2002 on mailinglist users@ipv6.org )
Chapter 16. Auto-configuration
Table of Contents
1._Stateless_auto-configuration_out-of-the-box
2._Stateless_auto-configuration_using_Router_Advertisement_Daemon_(radvd)
3._Dynamic_Host_Configuration_Protocol_v6_(DHCPv6)
1. Stateless auto-configuration out-of-the-box
Is supported and seen on the assigned link-local address after an IPv6-enabled
interface is up.
Example:
# ip -6 addr show dev eth0 scope link
2: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qlen1000
inet6 fe80::211:d8ff:fe6b:f0f5/64 scope link
valid_lft forever preferred_lft forever
2. Stateless auto-configuration using Router Advertisement Daemon (radvd)
to be filled. See radvd_daemon_autoconfiguration below.
3. Dynamic Host Configuration Protocol v6 (DHCPv6)
After a long time discussing issues, finally RFC_3315_/_Dynamic_Host
Configuration_Protocol_for_IPv6_(DHCPv6) was finished. At time updating this
part (10/2005) currently two implementations are available:
* Dibbler by Tomasz Mrugalski <thomson at klub dot com dot pl> (Hints_for
configuration)
* dhcpv6 (Hints_for_configuration)
* ISC_DHCP (Hints_for_configuration)
Chapter 17. Mobility
Table of Contents
1._Common_information
1.1._Node_Mobility
1.2._Network_Mobility
1.3._Links
1. Common information
1.1. Node Mobility
Support for IPv6 mobility can be enabled in Linux by installing the MIPL2
implementation found at: http://www.mobile-ipv6.org/
This implementation is compliant with RFC 3775. It is composed of a kernel
patch and a mobility daemon called mip6d. Version 2.0.1 applies on Linux kernel
2.6.15.
Installation and setup are described in the Linux_Mobile_IPv6_HOWTO.
1.2. Network Mobility
There also exists an implementation of network mobility for Linux, it is called
NEPL and is based on MIPL. It can also be downloaded from: http://www.mobile-
ipv6.org/.
The HOWTO document describing setup and configuration is available at: http://
www.nautilus6.org/doc/nepl-howto/.
1.3. Links
* Mobile IPv6 for Linux (MIPL) project: http://www.mobile-ipv6.org/
* Nautilus6 working group: http://nautilus6.org/
* Fast Handovers for Mobile IPv6 for Linux project: http://www.fmipv6.org/
* USAGI-patched Mobile IPv6 for Linux (UMIP):http://umip.linux-ipv6.org/
* Deploying IPsec/IKE-protected MIPv6 under Linux:http://natisbad.org/MIPv6/
* RFC_3775_/_Mobility_Support_in_IPv6
* RFC_3776_/_Using_IPsec_to_Protect_Mobile_IPv6_Signaling_Between_Mobile_Nodes
and_Home_Agents
* RFC_3963_/_Network_Mobility_(NEMO)
* RFC_4068_/_Fast_Handovers_for_Mobile_IPv6
* RFC_4423_/_Host_Identity_Protocol_(HIP)_Architecture
* RFC_5201_/_Host_Identity_Protocol
* HIP implementations: http://infrahip.hiit.fi/, http://hip4inter.net/, http://
www.openhip.org/
Chapter 18. Firewalling
Table of Contents
1._Firewalling_using_netfilter6
1.1._More_information
2._Preparation
2.1._Get_sources
2.2._Extract_sources
2.3._Apply_latest_iptables/IPv6-related_patches_to_kernel_source
2.4._Configure,_build_and_install_new_kernel
2.5._Rebuild_and_install_binaries_of_iptables
3._Usage_of_ip6tables
3.1._Check_for_support
3.2._Learn_how_to_use_ip6tables
3.3._Examples
4._Network_Address_Translation_(NAT)_using_netfilter6
4.1._IPv6_Masquerading
4.2._IPv6_Destination_NAT
4.3._IPv6_Port_Forwarding
5._Firewalling_using_nftables
5.1._Preparation_for_nftables_usage
5.2._Basic_nftables_configuration
5.3._Simple_filter_policy_with_nftables_using_only_table_â€inetâ€
5.4._Filter_policy_with_nftables_using_tables_â€ipâ€,_â€ip6â€_and_â€inetâ€
IPv6 firewalling is important, especially if using IPv6 on internal networks
with global IPv6 addresses. Because unlike at IPv4 networks where in common
internal hosts are protected automatically using private IPv4 addresses like
RFC_1918_/_Address_Allocation_for_Private_Internets or Automatic Private IP
Addressing (APIPA)Google_search_for_Microsoft_+_APIPA, in IPv6 normally global
addresses are used and someone with IPv6 connectivity can reach all internal
IPv6 enabled nodes.
1. Firewalling using netfilter6
Native IPv6 firewalling is only supported in kernel versions 2.4+. In older
2.2- you can only filter IPv6-in-IPv4 by protocol 41.
Attention: no warranty that described rules or examples can really protect your
system!
Audit your ruleset after installation, see Section 3,_“IPv6_security_auditingâ€
for more.
Since kernel version 2.6.20 (February 2007) IPv6 connection tracking is fully
working (and does not break IPv4 NAT anymore like versions before)
Since kernel version 3.9.0 (April 2013) NAT for IPv6 is supported with
ip6tables >= 1.4.18
Since kernel version 3.13 (April 2014) new framework introduced named: nftables
1.1. More information
* Netfilter_project
* maillist_archive_of_netfilter_users
* maillist_archive_of_netfilter_developers
* Unofficial_status_informations
2. Preparation
This step is only needed if distributed kernel and netfilter doesn't fit your
requirements and new features are available but still not built-in.
2.1. Get sources
Get the latest kernel source: http://www.kernel.org/
Get the latest iptables package:
* Source tarball (for kernel patches): http://www.netfilter.org/
2.2. Extract sources
Change to source directory:
# cd /path/to/src
Unpack and rename kernel sources
# tar z|jxf kernel-version.tar.gz|bz2
# mv linux linux-version-iptables-version+IPv6
Unpack iptables sources
# tar z|jxf iptables-version.tar.gz|bz2
2.3. Apply latest iptables/IPv6-related patches to kernel source
Change to iptables directory
# cd iptables-version
Apply pending patches
# make pending-patches KERNEL_DIR=/path/to/src/linux-version-iptables-
version/
Apply additional IPv6 related patches (still not in the vanilla kernel
included)
# make patch-o-matic KERNEL_DIR=/path/to/src/linux-version-iptables-version/
Say yes at following options (iptables-1.2.2)
* ah-esp.patch
* masq-dynaddr.patch (only needed for systems with dynamic IP assigned WAN
connections like PPP or PPPoE)
* ipv6-agr.patch.ipv6
* ipv6-ports.patch.ipv6
* LOG.patch.ipv6
* REJECT.patch.ipv6
Check IPv6 extensions
# make print-extensions
Extensions found: IPv6:owner IPv6:limit IPv6:mac IPv6:multiport
2.4. Configure, build and install new kernel
Change to kernel sources
# cd /path/to/src/linux-version-iptables-version/
Edit Makefile
- EXTRAVERSION =
+ EXTRAVERSION = -iptables-version+IPv6-try
Run configure, enable IPv6 related
Code maturity level options
Prompt for development and/or incomplete code/drivers : yes
Networking options
Network packet filtering: yes
The IPv6 protocol: module
IPv6: Netfilter Configuration
IP6 tables support: module
All new options like following:
limit match support: module
MAC address match support: module
Multiple port match support: module
Owner match support: module
netfilter MARK match support: module
Aggregated address check: module
Packet filtering: module
REJECT target support: module
LOG target support: module
Packet mangling: module
MARK target support: module
Configure other related to your system, too
Compilation and installing: see the kernel section here and other HOWTOs
2.5. Rebuild and install binaries of iptables
Make sure, that upper kernel source tree is also available at /usr/src/linux/
Rename older directory
# mv /usr/src/linux /usr/src/linux.old
Create a new softlink
# ln -s /path/to/src/linux-version-iptables-version /usr/src/linux
Rebuild SRPMS
# rpm --rebuild /path/to/SRPMS/iptables-version-release.src.rpm
Install new iptables packages (iptables + iptables-ipv6)
* On RH 7.1 systems, normally, already an older version is installed, therefore
use "freshen"
# rpm -Fhv /path/to/RPMS/cpu/iptables*-version-release.cpu.rpm
* If not already installed, use "install"
# rpm -ihv /path/to/RPMS/cpu/iptables*-version-release.cpu.rpm
* On RH 6.2 systems, normally, no kernel 2.4.x is installed, therefore the
requirements don't fit. Use "--nodeps" to install it
# rpm -ihv --nodeps /path/to/RPMS/cpu/iptables*-version-release.cpu.rpm
Perhaps it's necessary to create a softlink for iptables libraries where
iptables looks for them
# ln -s /lib/iptables/ /usr/lib/iptables
3. Usage of ip6tables
3.1. Check for support
Load module, if so compiled
# modprobe ip6_tables
Check for capability
# [ ! -f /proc/net/ip6_tables_names ] && echo "Current kernel doesn't
support
¬ 'ip6tables' firewalling (IPv6)!"
3.2. Learn how to use ip6tables
3.2.1. List all IPv6 netfilter entries
* Short
# ip6tables -L
* Extended
# ip6tables -n -v --line-numbers -L
3.2.2. List specified filter
# ip6tables -n -v --line-numbers -L INPUT
3.2.3. Insert a log rule at the input filter with options
# ip6tables --table filter --append INPUT -j LOG --log-prefix "INPUT:"
¬ --log-level 7
3.2.4. Insert a drop rule at the input filter
# ip6tables --table filter --append INPUT -j DROP
3.2.5. Delete a rule by number
# ip6tables --table filter --delete INPUT 1
3.2.6. Enable connection tracking
Since kernel version 2.6.20 IPv6 connection tracking is well supported and
should be used instead of using stateless filter rules.
# ip6tables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
3.2.7. Allow ICMPv6
Using older kernels (unpatched kernel 2.4.5 and iptables-1.2.2) no type can be
specified
* Accept incoming ICMPv6 through tunnels
# ip6tables -A INPUT -i sit+ -p icmpv6 -j ACCEPT
* Allow outgoing ICMPv6 through tunnels
# ip6tables -A OUTPUT -o sit+ -p icmpv6 -j ACCEPT
Newer kernels allow specifying of ICMPv6 types:
# ip6tables -A INPUT -p icmpv6 --icmpv6-type echo-request -j ACCEPT
3.2.8. Rate-limiting
Because it can happen (author already saw it to times) that an ICMPv6 storm
will raise up, you should use available rate limiting for at least ICMPv6
ruleset. In addition logging rules should also get rate limiting to prevent DoS
attacks against syslog and storage of log file partition. An example for a rate
limited ICMPv6 looks like:
# ip6tables -A INPUT --protocol icmpv6 --icmpv6-type echo-request
¬ -j ACCEPT --match limit --limit 30/minute
3.2.9. Allow incoming SSH
Here an example is shown for a ruleset which allows incoming SSH connection
from a specified IPv6 address
* Allow incoming SSH from 2001:0db8:100::1/128
# ip6tables -A INPUT -i sit+ -p tcp -s 2001:0db8:100::1/128 --sport 512:65535
¬ --dport 22 -j ACCEPT
* Allow response packets (no longer needed if connection tracking is used!)
# ip6tables -A OUTPUT -o sit+ -p tcp -d 2001:0db8:100::1/128 --dport 512:
65535
¬ --sport 22 ! --syn -j ACCEPT
3.2.10. Enable tunneled IPv6-in-IPv4
To accept tunneled IPv6-in-IPv4 packets, you have to insert rules in your IPv4
firewall setup relating to such packets, for example
* Accept incoming IPv6-in-IPv4 on interface ppp0
# iptables -A INPUT -i ppp0 -p ipv6 -j ACCEPT
* Allow outgoing IPv6-in-IPv4 to interface ppp0
# iptables -A OUTPUT -o ppp0 -p ipv6 -j ACCEPT
If you have only a static tunnel, you can specify the IPv4 addresses, too, like
* Accept incoming IPv6-in-IPv4 on interface ppp0 from tunnel endpoint 192.0.2.2
# iptables -A INPUT -i ppp0 -p ipv6 -s 192.0.2.2 -j ACCEPT
* Allow outgoing IPv6-in-IPv4 to interface ppp0 to tunnel endpoint 192.0.2.2
# iptables -A OUTPUT -o ppp0 -p ipv6 -d 192.0.2.2 -j ACCEPT
3.2.11. Protection against incoming TCP connection requests
VERY RECOMMENDED! For security issues you should really insert a rule which
blocks incoming TCP connection requests. Adapt "-i" option, if other interface
names are in use!
* Block incoming TCP connection requests to this host
# ip6tables -I INPUT -i sit+ -p tcp --syn -j DROP
* Block incoming TCP connection requests to hosts behind this router
# ip6tables -I FORWARD -i sit+ -p tcp --syn -j DROP
Perhaps the rules have to be placed below others, but that is work you have to
think about it. Best way is to create a script and execute rules in a specified
way.
3.2.12. Protection against incoming UDP connection requests
ALSO RECOMMENDED! Like mentioned on my firewall information it's possible to
control the ports on outgoing UDP/TCP sessions. So if all of your local IPv6
systems are using local ports e.g. from 32768 to 60999 you are able to filter
UDP connections also (until connection tracking works) like:
* Block incoming UDP packets which cannot be responses of outgoing requests of
this host
# ip6tables -I INPUT -i sit+ -p udp ! --dport 32768:60999 -j DROP
* Block incoming UDP packets which cannot be responses of forwarded requests of
hosts behind this router
# ip6tables -I FORWARD -i sit+ -p udp ! --dport 32768:60999 -j DROP
3.3. Examples
3.3.1. Simple example for Fedora
Following lines show a simple firewall configuration for Fedora 6 (since kernel
version 2.6.20). It was modfied from the default one (generated by system-
config-firewall) for supporting connection tracking and return the proper
ICMPv6 code for rejects. Incoming SSH (port 22) connections are allowed.
File: /etc/sysconfig/ip6tables
*filter :INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:RH-Firewall-1-INPUT - [0:0]
-A INPUT -j RH-Firewall-1-INPUT
-A FORWARD -j RH-Firewall-1-INPUT
-A RH-Firewall-1-INPUT -i lo -j ACCEPT
-A RH-Firewall-1-INPUT -p icmpv6 -j ACCEPT
-A RH-Firewall-1-INPUT -p 50 -j ACCEPT
-A RH-Firewall-1-INPUT -p 51 -j ACCEPT
-A RH-Firewall-1-INPUT -p udp --dport 5353 -d ff02::fb -j ACCEPT
-A RH-Firewall-1-INPUT -p udp -m udp --dport 631 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m tcp --dport 631 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -p tcp --dport 22 -j ACCEPT
-A RH-Firewall-1-INPUT -j REJECT --reject-with icmp6-adm-prohibited
COMMIT
For completeness also the IPv4 configuration is shown here:
File: /etc/sysconfig/iptables
*filter :INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:RH-Firewall-1-INPUT - [0:0]
-A INPUT -j RH-Firewall-1-INPUT
-A FORWARD -j RH-Firewall-1-INPUT
-A RH-Firewall-1-INPUT -i lo -j ACCEPT
-A RH-Firewall-1-INPUT -p icmp --icmp-type any -j ACCEPT
-A RH-Firewall-1-INPUT -p 50 -j ACCEPT
-A RH-Firewall-1-INPUT -p 51 -j ACCEPT
-A RH-Firewall-1-INPUT -p udp --dport 5353 -d 224.0.0.251 -j ACCEPT
-A RH-Firewall-1-INPUT -p udp -m udp --dport 631 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m tcp --dport 631 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 22 -
j ACCEPT
-A RH-Firewall-1-INPUT -j REJECT --reject-with icmp-host-prohibited
COMMIT
Usage:
* Create/modify the configuration files
* Activate IPv4 & IPv6 firewalling
# service iptables start
# service ip6tables start
* Enable automatic start after reboot
# chkconfig iptables on
# chkconfig ip6tables on
3.3.2. Sophisticated example
Following lines show a more sophisticated but still stateless filter setup as
an example. Happy netfilter6 ruleset creation....
# ip6tables -n -v -L
Chain INPUT (policy DROP 0 packets, 0 bytes)
pkts bytes target prot opt in out source
destination
0 0 extIN all sit+ * ::/0 ::/0
4 384 intIN all eth0 * ::/0 ::/0
0 0 ACCEPT all * * ::1/128 ::1/128
0 0 ACCEPT all lo * ::/0 ::/0
0 0 LOG all * * ::/0 ::/
0
¬ LOG flags 0 level 7 prefix `INPUT-default:'
0 0 DROP all * * ::/0 ::/0
Chain FORWARD (policy DROP 0 packets, 0 bytes)
pkts bytes target prot opt in out source
destination
¬
0 0 int2ext all eth0 sit+ ::/0 ::/0
0 0 ext2int all sit+ eth0 ::/0 ::/0
0 0 LOG all * * ::/0 ::/
0
¬ LOG flags 0 level 7 prefix `FORWARD-default:'
0 0 DROP all * * ::/0 ::/0
Chain OUTPUT (policy DROP 0 packets, 0 bytes)
pkts bytes target prot opt in out source
destination
¬
0 0 extOUT all * sit+ ::/0 ::/0
4 384 intOUT all * eth0 ::/0 ::/0
0 0 ACCEPT all * * ::1/128 ::1/128
0 0 ACCEPT all * lo ::/0 ::/0
0 0 LOG all * * ::/0 ::/
0
¬ LOG flags 0 level 7 prefix `OUTPUT-default:'
0 0 DROP all * * ::/0 ::/0
Chain ext2int (1 references)
pkts bytes target prot opt in out source
destination
¬
0 0 ACCEPT icmpv6 * * ::/0 ::/0
0 0 ACCEPT tcp * * ::/0 ::/
0
¬ tcp spts:1:65535 dpts:1024:65535 flags:!0x16/0x02
0 0 LOG all * * ::/0 ::/
0
¬ LOG flags 0 level 7 prefix `ext2int-default:'
0 0 DROP tcp * * ::/0 ::/0
0 0 DROP udp * * ::/0 ::/0
0 0 DROP all * * ::/0 ::/0
Chain extIN (1 references)
pkts bytes target prot opt in out source
destination
¬
0 0 ACCEPT tcp * * 3ffe:400:100::1/128 ::/
0
¬ tcp spts:512:65535 dpt:22
0 0 ACCEPT tcp * * 3ffe:400:100::2/128 ::/
0
¬ tcp spts:512:65535 dpt:22
0 0 ACCEPT icmpv6 * * ::/0 ::/0
0 0 ACCEPT tcp * * ::/0 ::/
0
¬ tcp spts:1:65535 dpts:1024:65535 flags:!0x16/0x02
0 0 ACCEPT udp * * ::/0 ::/
0
¬ udp spts:1:65535 dpts:1024:65535
0 0 LOG all * * ::/0 ::/
0
¬ limit: avg 5/min burst 5 LOG flags 0 level 7 prefix `extIN-default:
'
0 0 DROP all * * ::/0 ::/0
Chain extOUT (1 references)
pkts bytes target prot opt in out source
destination
¬
0 0 ACCEPT tcp * * ::/0
¬ 2001:0db8:100::1/128tcp spt:22 dpts:512:65535 flags:!0x16/0x02
0 0 ACCEPT tcp * * ::/0
¬ 2001:0db8:100::2/128tcp spt:22 dpts:512:65535 flags:!0x16/0x02
0 0 ACCEPT icmpv6 * * ::/0 ::/0
0 0 ACCEPT tcp * * ::/0 ::/
0
¬ tcp spts:1024:65535 dpts:1:65535
0 0 ACCEPT udp * * ::/0 ::/
0
¬ udp spts:1024:65535 dpts:1:65535
0 0 LOG all * * ::/0 ::/
0
¬ LOG flags 0 level 7 prefix `extOUT-default:'
0 0 DROP all * * ::/0 ::/0
Chain int2ext (1 references)
pkts bytes target prot opt in out source
destination
¬
0 0 ACCEPT icmpv6 * * ::/0 ::/0
0 0 ACCEPT tcp * * ::/0 ::/
0
¬ tcp spts:1024:65535 dpts:1:65535
0 0 LOG all * * ::/0 ::/
0
¬ LOG flags 0 level 7 prefix `int2ext:'
0 0 DROP all * * ::/0 ::/0
0 0 LOG all * * ::/0 ::/
0
¬ LOG flags 0 level 7 prefix `int2ext-default:'
0 0 DROP tcp * * ::/0 ::/0
0 0 DROP udp * * ::/0 ::/0
0 0 DROP all * * ::/0 ::/0
Chain intIN (1 references)
pkts bytes target prot opt in out source
destination
¬
0 0 ACCEPT all * * ::/0
¬ fe80::/ffc0::
4 384 ACCEPT all * * ::/0 ff02::/16
Chain intOUT (1 references)
pkts bytes target prot opt in out source
destination
¬
0 0 ACCEPT all * * ::/0
¬ fe80::/ffc0::
4 384 ACCEPT all * * ::/0 ff02::/16
0 0 LOG all * * ::/0 ::/
0
¬ LOG flags 0 level 7 prefix `intOUT-default:'
0 0 DROP all * * ::/0 ::/0
4. Network Address Translation (NAT) using netfilter6
Since at least Linux kernel version 3.9.0 and using ip6tables since 1.4.18 also
Network Address Translation (NAT) is usable.
4.1. IPv6 Masquerading
Like in IPv4 clients behind a router can be hided by using IPv6 masquerading
(hide/overlap NAT), e.g.
# ip6tables -t nat -A POSTROUTING -o sixxs -s fec0::/64 -j MASQUERADE
4.2. IPv6 Destination NAT
A dedicated public IPv6 address can be forwarded to an internal IPv6 address,
e.g.
# ip6tables -t nat -A PREROUTING -d 2001:db8:0:1:5054:ff:fe01:2345 -i sixxs -
j DNAT --to-destination fec0::5054:ff:fe01:2345
4.3. IPv6 Port Forwarding
A dedicated specified port can be forwarded to an internal system, e.g.
# ip6tables -t nat -A PREROUTING -i sixxs -p tcp --dport 8080 -j DNAT --to-
destination [fec0::1234]:80
5. Firewalling using nftables
nftables adds in addition to protocol specific tables â€ip†(IPv4) and â€ip6â€
(IPv6) support for a IPv4/IPv6 aware table named â€inetâ€. Using this table it's
possible to add only one rule and match both protocols (in case of UDP and
TCP).
Take care if rules are contained in more than one table, because the tables are
checked in sequence:
IPv4-Packet --> table "ip" --> table "inet" --> further checks
IPv6-Packet --> table "ip6" --> table "inet" --> further checks
If table â€ip6†accepts the packet, also table â€inet†must accept the packet,
otherwise it can be dropped by a later drop rule.
5.1. Preparation for nftables usage
Install a Linux distribution which has nftables support already included. At
time of writing (May 2014) at least Fedora Rawhide (upcoming version 21) has
support in conjunction with nftables version 0.2.0.
5.2. Basic nftables configuration
Load kernel modules:
# modprobe nf_tables
# modprobe nf_tables_ipv4
# modprobe nf_tables_ipv6
# modprobe nf_tables_inet
Flush iptables and ip6tables to avoid interferences:
# iptables -F
# ip6tables -F
Create filter table:
# nft add table inet filter
Create input chain:
# nft add chain inet filter input { type filter hook input priority 0 \; }
5.3. Simple filter policy with nftables using only table â€inetâ€
5.3.1. Configuration
Allow packets which are related to existing connection tracking entries
# nft add rule inet filter input ct state established,related counter accept
Allow IPv4 and IPv6 ICMP echo-request (aka ping)
# nft add rule inet filter input meta nfproto ipv4 icmp type { echo-request }
counter accept
# nft add rule inet filter input meta nfproto ipv6 icmpv6 type echo-request
counter accept
Allow some important IPv6 ICMP traffic, without counter, but checking hop-limit
for security
# nft add rule inet filter input meta nfproto ipv6
¬ icmpv6 type { nd-neighbor-advert, nd-neighbor-solicit, nd-router-advert}
ip6 hoplimit 1 accept
# nft add rule inet filter input meta nfproto ipv6
¬ icmpv6 type { nd-neighbor-advert, nd-neighbor-solicit, nd-router-advert}
ip6 hoplimit 255 counter accept
Allow incoming SSH for IPv4 and IPv6
# nft add rule inet filter input tcp dport 22 ct state new tcp flags \& \
(syn \| ack\) == syn counter accept
Reject/drop others
# nft add rule inet filter input tcp dport 0-65535 reject
# nft add rule inet filter input udp dport 0-65535 counter drop
# nft add rule inet filter input counter drop
5.3.2. Result
Table for IP version aware filter
table inet filter {
chain input {
type filter hook input priority 0;
ct state established,related counter packets 0 bytes 0 accept
ip protocol icmp icmp type { echo-request} counter packets 0 bytes 0
accept
ip6 nexthdr ipv6-icmp icmpv6 type echo-request counter packets 0 bytes 0
accept
ip6 nexthdr ipv6-icmp ip6 hoplimit 1 icmpv6 type { nd-neighbor-advert, nd-
neighbor-solicit, nd-router-advert} accept
ip6 nexthdr ipv6-icmp ip6 hoplimit 255 icmpv6 type { nd-neighbor-advert,
nd-neighbor-solicit, nd-router-advert} accept
tcp dport ssh ct state new tcp flags & (syn | ack) == syn counter
packets 0 bytes 0 accept
tcp dport >= 0 tcp dport <= 65535 counter packets 0 bytes 0 reject
udp dport >= 0 udp dport <= 65535 counter packets 0 bytes 0 drop
log prefix counter packets 0 bytes 0 drop
}
}
5.3.3. Hints for logging
To enable logging, an additonal kernel module must be loaded
# modprobe xt_LOG
BUT TAKE CARE, IT LOOKS LIKE THAT NO LOG LEVEL CAN BE SPEFICIED CURRENTLY IN
nftables, resulting that events are logged with kern.emerg - POSSIBILITY OF
FLODDING THE CONSOLE WITH LOG ENTRIES!
Fir initial test with logging it can be useful to disable kernel console
logging in e.g. /etc/rsyslog.conf by putting a â€#†in front of the related
entry and restart logging daemon
#*.emerg :omusrmsg:*
Rule from above accepting SSH on port 22, but now with logging:
# nft add rule inet filter input tcp dport 22 ct state new tcp flags \& \
(syn \| ack\) == syn log prefix \"inet/input/accept: \" counter accept
5.4. Filter policy with nftables using tables â€ipâ€, â€ip6†and â€inetâ€
As written above, if rules should be stored in related tables, it must be
assured that earlier accepts are not discarded in the further table. This can
be done using â€meta mark set xxxx†on every accept rule and generic rules which
accepts packets with â€mark xxxxâ€. A resulting filter set would look like the
following:
# for table in ip ip6 inet; do nft list table $table filter; done
table ip filter {
chain input {
type filter hook input priority 0;
ct state established,related counter packets 241 bytes 25193 accept
counter packets 2 bytes 120 mark 0x00000100 accept
icmp type { echo-request} counter packets 0 bytes 0 meta mark set
0x00000100 accept
}
}
table ip6 filter {
chain input {
type filter hook input priority 0;
ct state established,related counter packets 14 bytes 4077 accept
counter packets 4 bytes 408 mark 0x00000100 accept
icmpv6 type echo-request counter packets 1 bytes 104 meta mark set
0x00000100
icmpv6 type { nd-neighbor-advert, nd-neighbor-solicit, nd-router-advert}
counter packets 2 bytes 224 meta mark set 0x00000100 accept
}
}
table inet filter {
chain input {
type filter hook input priority 0;
ct state established,related counter packets 307 bytes 31974 accept
counter packets 6 bytes 528 mark 0x00000100 accept
tcp dport ssh ct state new tcp flags & (syn | ack) == syn log prefix
"inet/input/accept: " meta mark set 0x00000100 counter packets 3 bytes 200
accept
log prefix "inet/input/reject: " counter packets 0 bytes 0 reject
}
}
Chapter 19. Security
Table of Contents
1._Node_security
2._Access_limitations
3._IPv6_security_auditing
3.1._Legal_issues
3.2._Security_auditing_using_IPv6-enabled_netcat
3.3._Security_auditing_using_IPv6-enabled_nmap
3.4._Security_auditing_using_IPv6-enabled_strobe
3.5._Security_auditing_using_online_tools
3.6._Audit_results
1. Node security
It's very recommended to apply all available patches and disable all not
necessary services. Also bind services to the needed IPv4/IPv6 addresses only
and install local firewalling.
More to be filled...
2. Access limitations
Many services uses the tcp_wrapper library for access control. Below is
described the use_of_tcp_wrapper.
More to be filled...
3. IPv6 security auditing
Currently there are no comfortable tools out which are able to check a system
over network for IPv6 security issues. Neither Nessus nor any commercial
security scanner is as far as I know able to scan IPv6 addresses.
3.1. Legal issues
ATTENTION: always take care that you only scan your own systems or after
receiving a written order, otherwise legal issues are able to come up to you.
CHECK destination IPv6 addresses TWICE before starting a scan.
3.2. Security auditing using IPv6-enabled netcat
With the IPv6-enabled netcat (see IPv6+Linux-status-apps/security-auditing for
more) you can run a portscan by wrapping a script around which run through a
port range, grab banners and so on. Usage example:
# nc6 ::1 daytime
13 JUL 2002 11:22:22 CEST
3.3. Security auditing using IPv6-enabled nmap
NMap, one of the best portscaner around the world, supports IPv6 since version
3.10ALPHA1. Usage example:
# nmap -6 -sT ::1
Starting nmap V. 3.10ALPHA3 ( www.insecure.org/nmap/ )
Interesting ports on localhost6 (::1):
(The 1600 ports scanned but not shown below are in state: closed)
Port State Service
22/tcp open ssh
53/tcp open domain
515/tcp open printer
2401/tcp open cvspserver
Nmap run completed -- 1 IP address (1 host up) scanned in 0.525 seconds
3.4. Security auditing using IPv6-enabled strobe
Strobe is a (compared to NMap) more a low budget portscanner, but there is an
IPv6-enabling patch available (see IPv6+Linux-status-apps/security-auditing for
more). Usage example:
# ./strobe ::1 strobe 1.05 (c) 1995-1999 Julian Assange <proff@iq.org>.
::1 2401 unassigned unknown
::1 22 ssh Secure Shell - RSA encrypted rsh
::1 515 printer spooler (lpd)
::1 6010 unassigned unknown
::1 53 domain Domain Name Server
Note: strobe isn't really developed further on, the shown version number isn't
the right one.
3.5. Security auditing using online tools
There are some IPv6 enabled online tools available which can support in testing
inbound firewall configuration:
* Tim's_Online_IPv6_TCP/UDP_Port_Scanner
* SubnetOnline_IPv6_Scanner
3.6. Audit results
If the result of an audit mismatch your IPv6 security policy, use IPv6
firewalling to close the holes, e.g. using netfilter6 (see Firewalling/
Netfilter6 for more).
Info: More detailed information concerning IPv6 Security can be found here:
* IETF_drafts_-_IPv6_Operations_(v6ops)
* RFC_3964_/_Security_Considerations_for_6to4
Chapter 20. Encryption and Authentication
Table of Contents
1._Modes_of_using_encryption_and_authentication
1.1._Transport_mode
1.2._Tunnel_mode
2._Support_in_kernel_(ESP_and_AH)
2.1._Support_in_vanilla_Linux_kernel_2.4.x
2.2._Support_in_vanilla_Linux_kernel_2.6.x
3._Automatic_key_exchange_(IKE)
3.1._IKE_daemon_â€racoonâ€
3.2._IKE_daemon_â€plutoâ€
4._Additional_informations:
Unlike in IPv4, encryption and authentication is a mandatory feature of IPv6.
Those features are normally implemented using IPsec (which can be also used by
IPv4).
1. Modes of using encryption and authentication
Two modes of encryption and authentication of a connection are possible:
1.1. Transport mode
Transport mode is a real end-to-end connection mode. Here, only the payload
(usually ICMP, TCP or UDP) is encrypted with their particular header, while the
IP header is not encrypted (but usually included in authentication).
Using AES-128 for encryption and SHA1 for authentication, this mode decreases
the MTU by 42 octets.
1.2. Tunnel mode
Tunnel mode can be used either for end-to-end or for gateway-to-gateway
connection modes. Here, the complete IP packet is being encrypted and gets a
new IP header prepended, all together constituing a new IP packet (this
mechanism is also known as "encapsulation")
This mode usually decreases the MTU by 40 octets from the MTU of transport
mode. I.e. using AES-128 for encryption and SHA1 for authentication 82 octets
less than the normal MTU.
2. Support in kernel (ESP and AH)
2.1. Support in vanilla Linux kernel 2.4.x
At the time of writing missing in vanilla up to 2.4.28. There was an issue
about keeping the Linux kernel source free of export/import-control-laws
regarding encryption code. This is also one case why FreeS/WAN_project wasn't
included in vanilla source. Perhaps a backport from 2.6.x will be done in the
future.
2.2. Support in vanilla Linux kernel 2.6.x
Current versions (as time of writing 2.6.9 and upper) support native IPsec for
IPv4 and IPv6.
Implementation was helped by the USAGI project.
3. Automatic key exchange (IKE)
IPsec requires a key exchange of a secret. This is mostly done automatically by
so called IKE daemons. They also handle the authentication of the peers, either
by a common known secret (so called â€pre-shared secretâ€) or by RSA keys (which
can also be used from X.509 certificates).
Currently, two different IKE daemons are available for Linux, which totally
differ in configuration and usage.
I prefer â€pluto†from the *S/WAN implementation because of the easier and one-
config-only setup.
3.1. IKE daemon â€racoonâ€
The IKE daemon â€racoon†is taken from the KAME project and ported to Linux.
Modern Linux distributions contain this daemon in the package â€ipsec-toolsâ€.
Two executables are required for a proper IPsec setup. Take a look on Linux
Advanced_Routing_&_Traffic_Control_HOWTO_/_IPSEC, too.
3.1.1. Manipulation of the IPsec SA/SP database with the tool â€setkeyâ€
â€setkey†is important to define the security policy (SP) for the kernel.
File: /etc/racoon/setkey.sh
* Example for an end-to-end encrypted connection in transport mode
#!/sbin/setkey -f
flush;
spdflush;
spdadd 2001:db8:1:1::1 2001:db8:2:2::2 any -P out ipsec esp/transport//
require;
spdadd 2001:db8:2:2::2 2001:db8:1:1::1 any -P in ipsec esp/transport//
require;
* Example for a end-to-end encrypted connection in tunnel mode
#!/sbin/setkey -f
flush;
spdflush;
spdadd 2001:db8:1:1::1 2001:db8:2:2::2 any -P out ipsec
¬ esp/tunnel/2001:db8:1:1::1-2001:db8:2:2::2/require;
spdadd 2001:db8:2:2::2 2001:db8:1:1::1 any -P in ipsec
¬ esp/tunnel/2001:db8:2:2::2-2001:db8:1:1::1/require;
For the other peer, you have to replace â€in†with â€outâ€.
3.1.2. Configuration of the IKE daemon â€racoonâ€
â€racoon†requires a configuration file for proper execution. It includes the
related settings to the security policy, which should be set up previously
using â€setkeyâ€.
File: /etc/racoon/racoon.conf
# Racoon IKE daemon configuration file.
# See 'man racoon.conf' for a description of the format and entries.
path include "/etc/racoon";
path pre_shared_key "/etc/racoon/psk.txt";
listen
{
isakmp 2001:db8:1:1::1;
}
remote 2001:db8:2:2::2
{
exchange_mode main;
lifetime time 24 hour;
proposal
{
encryption_algorithm 3des;
hash_algorithm md5;
authentication_method pre_shared_key;
dh_group 2;
}
}
# gateway-to-gateway
sainfo address 2001:db8:1:1::1 any address 2001:db8:2:2::2 any
{
lifetime time 1 hour;
encryption_algorithm 3des;
authentication_algorithm hmac_md5;
compression_algorithm deflate;
}
sainfo address 2001:db8:2:2::2 any address 2001:db8:1:1::1 any
{
lifetime time 1 hour;
encryption_algorithm 3des;
authentication_algorithm hmac_md5;
compression_algorithm deflate;
}
Also set up the pre-shared secret:
File: /etc/racoon/psk.txt
# file for pre-shared keys used for IKE authentication
# format is: 'identifier' 'key'
2001:db8:2:2::2 verysecret
3.1.3. Running IPsec with IKE daemon â€racoonâ€
At least the daemon needs to be started. For the first time, use debug and
foreground mode. The following example shows a successful IKE phase 1 (ISAKMP-
SA) and 2 (IPsec-SA) negotiation:
# racoon -F -v -f /etc/racoon/racoon.conf
Foreground mode.
2005-01-01 20:30:15: INFO: @(#)ipsec-tools 0.3.3
¬ (http://ipsec-tools.sourceforge.net)
2005-01-01 20:30:15: INFO: @(#)This product linked
¬ OpenSSL 0.9.7a Feb 19 2003 (http://www.openssl.org/)
2005-01-01 20:30:15: INFO: 2001:db8:1:1::1[500] used as isakmp port (fd=7)
2005-01-01 20:31:06: INFO: IPsec-SA request for 2001:db8:2:2::2
¬ queued due to no phase1 found.
2005-01-01 20:31:06: INFO: initiate new phase 1 negotiation:
¬ 2001:db8:1:1::1[500]<=>2001:db8:2:2::2[500]
2005-01-01 20:31:06: INFO: begin Identity Protection mode.
2005-01-01 20:31:09: INFO: ISAKMP-SA established
¬ 2001:db8:1:1::1[500]-2001:db8:2:2::2[500] spi:da3d3693289c9698:
ac039a402b2db401
2005-01-01 20:31:09: INFO: initiate new phase 2 negotiation:
¬ 2001:6f8:900:94::2[0]<=>2001:db8:2:2::2[0]
2005-01-01 20:31:10: INFO: IPsec-SA established:
¬ ESP/Tunnel 2001:db8:2:2::2->2001:db8:1:1::1 spi=253935531(0xf22bfab)
2005-01-01 20:31:10: INFO: IPsec-SA established:
¬ ESP/Tunnel 2001:db8:1:1::1->2001:db8:2:2::2 spi=175002564(0xa6e53c4)
Each direction got its own IPsec-SA (like defined in the IPsec standard). With
â€tcpdump†on the related interface, you will see as result of an IPv6 ping:
20:35:55.305707 2001:db8:1:1::1 > 2001:db8:2:2::2: ESP
(spi=0x0a6e53c4,seq=0x3)
20:35:55.537522 2001:db8:2:2::2 > 2001:db8:1:1::1: ESP
(spi=0x0f22bfab,seq=0x3)
As expected, the negotiated SPIs are being used here.
And using â€setkeyâ€, current active parameters are shown:
# setkey -D
2001:db8:1:1::1 2001:db8:2:2::2
esp mode=tunnel spi=175002564(0x0a6e53c4) reqid=0(0x00000000)
E: 3des-cbc bd26bc45 aea0d249 ef9c6b89 7056080f 5d9fa49c 924e2edd
A: hmac-md5 60c2c505 517dd8b7 c9609128 a5efc2db
seq=0x00000000 replay=4 flags=0x00000000 state=mature
created: Jan 1 20:31:10 2005 current: Jan 1 20:40:47 2005
diff: 577(s) hard: 3600(s) soft: 2880(s)
last: Jan 1 20:35:05 2005 hard: 0(s) soft: 0(s)
current: 540(bytes) hard: 0(bytes) soft: 0(bytes)
allocated: 3 hard: 0 soft: 0
sadb_seq=1 pid=22358 refcnt=0
2001:db8:2:2::2 2001:db8:1:1::1
esp mode=tunnel spi=253935531(0x0f22bfab) reqid=0(0x00000000)
E: 3des-cbc c1ddba65 83debd62 3f6683c1 20e747ac 933d203f 4777a7ce
A: hmac-md5 3f957db9 9adddc8c 44e5739d 3f53ca0e
seq=0x00000000 replay=4 flags=0x00000000 state=mature
created: Jan 1 20:31:10 2005 current: Jan 1 20:40:47 2005
diff: 577(s) hard: 3600(s) soft: 2880(s)
last: Jan 1 20:35:05 2005 hard: 0(s) soft: 0(s)
current: 312(bytes) hard: 0(bytes) soft: 0(bytes)
allocated: 3 hard: 0 soft: 0
sadb_seq=0 pid=22358 refcnt=0
3.2. IKE daemon â€plutoâ€
The IKE daemon â€pluto†is included in distributions of the *S/WAN projects. *S/
WAN project starts at the beginning as FreeS/WAN. Unfortunately, the FreeS/WAN
project stopped further development in 2004. Because of the slow pace of
development in the past, two spin-offs started: strongSwan and Openswan. Today,
readily installable packages are available for at least Openswan (included in
Fedora Core 3).
A major difference to â€racoonâ€, only one configuration file is required. Also,
an initscript exists for automatic setup after booting.
3.2.1. Configuration of the IKE daemon â€plutoâ€
The configuration is very similar to the IPv4 one, only one important option is
necessary.
File: /etc/ipsec.conf
# /etc/ipsec.conf - Openswan IPsec configuration file
#
# Manual: ipsec.conf.5
version 2.0 # conforms to second version of ipsec.conf specification
# basic configuration
config setup
# Debug-logging controls: "none" for (almost) none, "all" for lots.
# klipsdebug=none
# plutodebug="control parsing"
#Disable Opportunistic Encryption
include /etc/ipsec.d/examples/no_oe.conf
conn ipv6-p1-p2
connaddrfamily=ipv6 # Important for IPv6, but no longer needed
since StrongSwan 4
left=2001:db8:1:1::1
right=2001:db8:2:2::2
authby=secret
esp=aes128-sha1
ike=aes128-sha-modp1024
type=transport
#type=tunnel
compress=no
#compress=yes
auto=add
#auto=up
Don't forget to define the pre-shared secret here also.
File: /etc/ipsec.secrets
2001:db8:1:1::1 2001:db8:2:2::2 : PSK "verysecret"
3.2.2. Running IPsec with IKE daemon â€plutoâ€
If installation of Openswan was successfully, an initscript should exist for
starting IPsec, simply run (on each peer):
# /etc/rc.d/init.d/ipsec start
Afterwards, start this connection on one peer. If you saw the line â€IPsec SA
establishedâ€, all worked fine.
# ipsec auto --up ipv6-peer1-peer2
104 "ipv6-p1-p2" #1: STATE_MAIN_I1: initiate
106 "ipv6-p1-p2" #1: STATE_MAIN_I2: sent MI2, expecting MR2
108 "ipv6-p1-p2" #1: STATE_MAIN_I3: sent MI3, expecting MR3
004 "ipv6-p1-p2" #1: STATE_MAIN_I4: ISAKMP SA established
112 "ipv6-p1-p2" #2: STATE_QUICK_I1: initiate
004 "ipv6-p1-p2" #2: STATE_QUICK_I2: sent QI2,
¬ IPsec SA established {ESP=>0xa98b7710 <0xa51e1f22}
Because *S/WAN and setkey/racoon do use the same IPsec implementation in Linux
2.6.x kernel, â€setkey†can be used here too to show current active parameters:
# setkey -D
2001:db8:1:1::1 2001:db8:2:2::2
esp mode=transport spi=2844489488(0xa98b7710) reqid=16385(0x00004001)
E: aes-cbc 082ee274 2744bae5 7451da37 1162b483
A: hmac-sha1 b7803753 757417da 477b1c1a 64070455 ab79082c
seq=0x00000000 replay=64 flags=0x00000000 state=mature
created: Jan 1 21:16:32 2005 current: Jan 1 21:22:20 2005
diff: 348(s) hard: 0(s) soft: 0(s)
last: hard: 0(s) soft: 0(s)
current: 0(bytes) hard: 0(bytes) soft: 0(bytes)
allocated: 0 hard: 0 soft: 0
sadb_seq=1 pid=23825 refcnt=0
2001:db8:2:2::2 2001:db8:1:1::1
esp mode=transport spi=2770214690(0xa51e1f22) reqid=16385(0x00004001)
E: aes-cbc 6f59cc30 8d856056 65e07b76 552cac18
A: hmac-sha1 c7c7d82b abfca8b1 5440021f e0c3b335 975b508b
seq=0x00000000 replay=64 flags=0x00000000 state=mature
created: Jan 1 21:16:31 2005 current: Jan 1 21:22:20 2005
diff: 349(s) hard: 0(s) soft: 0(s)
last: hard: 0(s) soft: 0(s)
current: 0(bytes) hard: 0(bytes) soft: 0(bytes)
allocated: 0 hard: 0 soft: 0
sadb_seq=0 pid=23825 refcnt=0
4. Additional informations:
On Linux Kernel 2.6.x you can get the policy and status of IPsec also using
â€ipâ€:
# ip xfrm policy
...
# ip xfrm state
...
Chapter 21. Quality of Service (QoS)
Table of Contents
1._General
2._Linux_QoS_using_â€tcâ€
2.1._Example_for_a_constant_bitrate_queuing
IPv6 supports QoS with use of Flow Labels and Traffic Classes.
Additional infos:
* RFC_3697_/_IPv6_Flow_Label_Specification
1. General
Proper working QoS is only possible on the outgoing interface of a router or
host, where the bottleneck begins. Everything else is a hickup and not subject
to work as expected or has a successful result.
-------------->-------
Queue 1 \
--->--- ---->--------->--------->---------------
Big pipe Queue 2 Queue 1 / Queue 2 / Queue 3 Thin Pipe
--->---- ---->--------->--------->---------------
Queue 3 /
-------------->-------
2. Linux QoS using â€tcâ€
Linux is using â€tc†from the â€iproute2†package to configure traffic shaping,
generally described in the Linux_Advanced_Routing_&_Traffic_Control_HOWTO.
2.1. Example for a constant bitrate queuing
With the â€cbq†scheduler, pipes with constant bit rates can be defined.
2.1.1. Root qdisc definition
Define root qdisc with a bandwidth of 1000 MBit/s on eth1
# tc qdisc add dev eth1 root handle 1: cbq avpkt 1000 bandwidth 1000Mbit
2.1.2. QoS class definition
Define a class 1:1 with 1 MBit/s
# tc class add dev eth1 parent 1: classid 1:1 cbq rate 1Mbit allot 1500
bounded
Define a class 1:2 with 50 MBit/s
# tc class add dev eth1 parent 1: classid 1:2 cbq rate 50Mbit allot 1500
bounded
Define a class 1:3 with 10 MBit/s
# tc class add dev eth1 parent 1: classid 1:3 cbq rate 10Mbit allot 1500
bounded
Define a class 1:4 with 200 kBit/s
# tc class add dev eth1 parent 1: classid 1:4 cbq rate 200kbit allot 1500
bounded
2.1.3. QoS filter definition
Define a filter for IPv4 (protocol ip), TCP (match ip protocol 6 0xff)
destination port 5001 (match ip dport 5001 0xffff) using class 1:2 from above
# tc filter add dev eth1 parent 1: protocol ip u32 match ip protocol 6
0xff match ip dport 5001 0xffff flowid 1:1
Define a filter for IPv6 (protocol ip), TCP (match ip6 protocol 6 0xff)
destination port 5001 using class 1:2 from above
# tc filter add dev eth1 parent 1: protocol ipv6 u32 match ip6 protocol 6
0xff match ip6 dport 5001 0xffff flowid 1:2
Define a filter for IPv6 for packets having flow label 12345 (match ip6
flowlabel 12345 0x3ffff) using class 1:3 from above
# tc filter add dev eth1 parent 1: protocol ipv6 u32 match ip6 flowlabel
12345 0x3ffff flowid 1:3
Define a filter for IPv6 for packets having Linux iptables mark 32 (handle 32
fw) specified using class 1:4 from above
# tc filter add dev eth1 parent 1: protocol ipv6 handle 32 fw flowid 1:4
The last filter definition requires an entry in the ip6tables to mark a packet
# ip6tables -A POSTROUTING -t mangle -p tcp --dport 5003 -j MARK --set-mark
32
2.1.4. Testing filter definitions using iperf
Start on server side each one one separate console:
# iperf -V -s -p 5001
# iperf -V -s -p 5002
# iperf -V -s -p 5003
Start on client side and compare results:
# iperf -V -c SERVER-IPv4 -p 5001 (expected: 1 MBit/s)
# iperf -V -c SERVER-IPv6 -p 5001 (expected: 50 MBit/s)
# iperf -V -c SERVER-IPv4 -p 5002 (expected: >> 50 MBit/s && <=
1000 MBit/s)
# iperf -V -c SERVER-IPv6 -p 5002 (expected: >> 50 MBit/s && <=
1000 MBit/s)
# iperf -V -c SERVER-IPv4 -p 5003 (expected: >> 50 MBit/s && <=
1000 MBit/s)
# iperf -V -c SERVER-IPv6 -p 5003 (expected: 200 kBit/s)
The rate result should be as defined in the classes (see above), the results on
port 5002 should be very similar independend from used IP version.
Chapter 22. Hints for IPv6-enabled daemons
Table of Contents
1._Berkeley_Internet_Name_Domain_(BIND)_daemon_â€namedâ€
1.1._Listening_on_IPv6_addresses
1.2._IPv6_enabled_Access_Control_Lists_(ACL)
1.3._Sending_queries_with_dedicated_IPv6_address
1.4._Per_zone_defined_dedicated_IPv6_addresses
1.5._IPv6_DNS_zone_files_examples
1.6._Serving_IPv6_related_DNS_data
1.7._Checking_IPv6-enabled_connect
2._Internet_super_daemon_(xinetd)
3._Webserver_Apache2_(httpd2)
3.1._Listening_on_IPv6_addresses
4._Router_Advertisement_Daemon_(radvd)
4.1._Configuring_radvd
4.2._Debugging
5._Dynamic_Host_Configuration_v6_Server_(dhcp6s)
5.1._Configuration_of_the_DHCPv6_server_(dhcp6s)
5.2._Configuration_of_the_DHCPv6_client_(dhcp6c)
5.3._Usage
5.4._Debugging
6._ISC_Dynamic_Host_Configuration_Server_(dhcpd)
6.1._Configuration_of_the_ISC_DHCP_server_for_IPv6_(dhcpd)
6.2._Usage
7._DHCP_Server_Dibbler
7.1._Configuration_of_the_Dibbler_DHCP_server_for_IPv6
7.2._Usage
8._tcp_wrapper
8.1._Filtering_capabilities
8.2._Which_program_uses_tcp_wrapper
8.3._Usage
8.4._Logging
9._vsftpd
9.1._Listening_on_IPv6_addresses
10._proftpd
10.1._Listening_on_IPv6_addresses
11._Other_daemons
Here some hints are shown for IPv6-enabled daemons.
1. Berkeley Internet Name Domain (BIND) daemon â€namedâ€
IPv6 is supported since version 9. Always use newest available version. At
least version 9.1.3 must be used, older versions can contain remote exploitable
security holes.
1.1. Listening on IPv6 addresses
Note: unlike in IPv4 current versions doesn't allow to bind a server socket to
dedicated IPv6 addresses, so only any or none are valid. Because this can be a
security issue, check the Access Control List (ACL) section below, too!
1.1.1. Enable BIND named for listening on IPv6 address
To enable IPv6 for listening, following options are requested to change
options {
# sure other options here, too
listen-on-v6 { any; };
};
This should result after restart in e.g.
# netstat -lnptu |grep "named\W*$"
tcp 0 0 :::53 :::* LISTEN 1234/named
¬ # incoming TCP requests
udp 0 0 1.2.3.4:53 0.0.0.0:* 1234/named
¬ # incoming UDP requests to IPv4 1.2.3.4
udp 0 0 127.0.0.1:53 0.0.0.0:* 1234/named
¬ # incoming UDP requests to IPv4 localhost
udp 0 0 0.0.0.0:32868 0.0.0.0:* 1234/named
¬ # dynamic chosen port for outgoing queries
udp 0 0 :::53 :::* 1234/named
¬ # incoming UDP request to any IPv6
And a simple test looks like
# dig localhost @::1
and should show you a result.
1.1.2. Disable BIND named for listening on IPv6 address
To disable IPv6 for listening, following options are requested to change
options {
# sure other options here, too
listen-on-v6 { none; };
};
1.2. IPv6 enabled Access Control Lists (ACL)
IPv6 enabled ACLs are possible and should be used whenever it's possible. An
example looks like following:
acl internal-net {
127.0.0.1;
1.2.3.0/24;
2001:0db8:100::/56;
::1/128;
::ffff:1.2.3.4/128;
};
acl ns-internal-net {
1.2.3.4;
1.2.3.5;
2001:0db8:100::4/128;
2001:0db8:100::5/128;
};
This ACLs can be used e.g. for queries of clients and transfer zones to
secondary name-servers. This prevents also your caching name-server to be used
from outside using IPv6.
options {
# sure other options here, too
listen-on-v6 { none; };
allow-query { internal-net; };
allow-transfer { ns-internal-net; };
};
It's also possible to set the allow-queryand allow-transfer option for most of
single zone definitions, too.
1.3. Sending queries with dedicated IPv6 address
This option is not required, but perhaps needed:
query-source-v6 address <ipv6address|*> port <port|*>;
1.4. Per zone defined dedicated IPv6 addresses
It's also possible to define per zone some IPv6 addresses.
1.4.1. Transfer source address
Transfer source address is used for outgoing zone transfers:
transfer-source-v6 <ipv6addr|*> [port port];
1.4.2. Notify source address
Notify source address is used for outgoing notify messages:
notify-source-v6 <ipv6addr|*> [port port];
1.5. IPv6 DNS zone files examples
Some information can be also found at IPv6_DNS_Setup_Information_(article).
Perhaps also helpful is the IPv6_Reverse_DNS_zone_builder_for_BIND_8/9_
(webtool).
1.6. Serving IPv6 related DNS data
For IPv6 new types and root zones for reverse lookups are defined:
* AAAA and reverse IP6.INT: specified in RFC_1886_/_DNS_Extensions_to_support
IP_version_6, usable since BIND version 4.9.6
* A6, DNAME (DEPRECATED NOW!) and reverse IP6.ARPA: specified in RFC_2874_/_DNS
Extensions_to_Support_IPv6_Address_Aggregation_and_Renumbering, usable since
BIND 9, but see also an information about the current state at Domain_Name
System_Extension_(dnsext)
Perhaps filled later more content, for the meantime take a look at given RFCs
and
* AAAA and reverse IP6.INT: IPv6_DNS_Setup_Information
* A6, DNAME (DEPRECATED NOW!) and reverse IP6.ARPA: take a look into chapter 4
and 6 of the BIND 9 Administrator Reference Manual (ARM) distributed with the
bind-package or get this here: BIND_manual_version_9.3
Because IP6.INT is deprecated (but still in use), a DNS server which will
support IPv6 information has to serve both reverse zones.
1.6.1. Current best practice
Because there are some troubles around using the new formats, current best
practice is:
Forward lookup support:
* AAAA
Reverse lookup support:
* Reverse nibble format for zone ip6.int (FOR BACKWARD COMPATIBILITY)
* Reverse nibble format for zone ip6.arpa (RECOMMENDED)
1.7. Checking IPv6-enabled connect
To check, whether BIND named is listening on an IPv6 socket and serving data
see following examples.
1.7.1. IPv6 connect, but denied by ACL
Specifying a dedicated server for the query, an IPv6 connect can be forced:
$ host -t aaaa www.6bone.net 2001:0db8:200:f101::1
Using domain server:
Name: 2001:0db8:200:f101::1
Address: 2001:0db8:200:f101::1#53
Aliases:
Host www.6bone.net. not found: 5(REFUSED)
Related log entry looks like following:
Jan 3 12:43:32 gate named[12347]: client
¬ 2001:0db8:200:f101:212:34ff:fe12:3456#32770:
query denied
If you see such entries in the log, check whether requests from this client
should be allowed and perhaps review your ACL configuration.
1.7.2. Successful IPv6 connect
A successful IPv6 connect looks like following:
$ host -t aaaa www.6bone.net 2001:0db8:200:f101::1
Using domain server:
Name: 2001:0db8:200:f101::1
Address: 2001:0db8:200:f101::1#53
Aliases:
www.6bone.net. is an alias for 6bone.net.
6bone.net. has AAAA address 3ffe:b00:c18:1::10
2. Internet super daemon (xinetd)
IPv6 is supported since xinetd version around 1.8.9. Always use newest
available version. At least version 2.3.3 must be used, older versions can
contain remote exploitable security holes.
Some Linux distribution contain an extra package for the IPv6 enabled xinetd,
some others start the IPv6-enabled xinetd if following variable is set:
NETWORKING_IPV6="yes", mostly done by /etc/sysconfig/network (only valid for
Red Hat like distributions). In newer releases, one binary supports IPv4 and
IPv6.
If you enable a built-in service like e.g. daytime by modifying the
configuration file in /etc/xinetd.d/daytime like
# diff -u /etc/xinetd.d/daytime.orig /etc/xinetd.d/daytime
--- /etc/xinetd.d/daytime.orig Sun Dec 16 19:00:14 2001
+++ /etc/xinetd.d/daytime Sun Dec 16 19:00:22 2001
@@ -10,5 +10,5 @@
protocol = tcp
user = root
wait = no
- disable = yes
+ disable = no
}
After restarting the xinetd you should get a positive result like:
# netstat -lnptu -A inet6 |grep "xinetd*"
tcp 0 0 ::ffff:192.168.1.1:993 :::* LISTEN 12345/xinetd-ipv6
tcp 0 0 :::13 :::* LISTEN 12345/xinetd-ipv6 <- service
¬ daytime/tcp
tcp 0 0 ::ffff:192.168.1.1:143 :::* LISTEN 12345/xinetd-ipv6
Shown example also displays an IMAP and IMAP-SSL IPv4-only listening xinetd.
Note: earlier versions had a problem that an IPv4-only xinetd won't start on an
IPv6-enabled node and also the IPv6-enabled xinetd won't start on an IPv4-only
node. This is known to be fixed in later versions, at least version 2.3.11.
3. Webserver Apache2 (httpd2)
Apache web server supports IPv6 native by maintainers since 2.0.14. Available
patches for the older 1.3.x series are not current and shouldn't be used in
public environment, but available at KAME_/_Misc.
3.1. Listening on IPv6 addresses
Note: virtual hosts on IPv6 addresses are broken in versions until 2.0.28 (a
patch is available for 2.0.28). But always try latest available version first
because earlier versions had some security issues.
3.1.1. Virtual host listen on an IPv6 address only
Listen [2001:0db8:100::1]:80
<VirtualHost [2001:0db8:100::1]:80>
ServerName ipv6only.yourdomain.yourtopleveldomain
# ...sure more config lines
</VirtualHost>
3.1.2. Virtual host listen on an IPv6 and on an IPv4 address
Listen [2001:0db8:100::2]:80
Listen 1.2.3.4:80
<VirtualHost [2001:0db8:100::2]:80 1.2.3.4:80>
ServerName ipv6andipv4.yourdomain.yourtopleveldomain
# ...sure more config lines
</VirtualHost>
This should result after restart in e.g.
# netstat -lnptu |grep "httpd2\W*$"
tcp 0 0 1.2.3.4:80 0.0.0.0:* LISTEN 12345/httpd2
tcp 0 0 2001:0db8:100::1:80 :::* LISTEN 12345/httpd2
tcp 0 0 2001:0db8:100::2:80 :::* LISTEN 12345/httpd2
For simple tests use the telnet example already shown.
3.1.3. Additional notes
* Apache2 supports a method called â€sendfile†to speedup serving data. Some NIC
drivers also support offline checksumming. In some cases, this can lead to
connection problems and invalid TCP checksums. In this cases, disable
â€sendfile†either by recompiling using configure option â€--without-sendfileâ€
or by using the "EnableSendfile off" directive in configuration file.
4. Router Advertisement Daemon (radvd)
The router advertisement daemon is very useful on a LAN, if clients should be
auto-configured. The daemon itself should run on the Linux default IPv6 gateway
router (it's not required that this is also the default IPv4 gateway, so pay
attention who on your LAN is sending router advertisements).
You can specify some information and flags which should be contained in the
advertisement. Common used are
* Prefix (needed)
* Lifetime of the prefix
* Frequency of sending advertisements (optional)
After a proper configuration, the daemon sends advertisements through specified
interfaces and clients are hopefully receive them and auto-magically configure
addresses with received prefix and the default route.
4.1. Configuring radvd
4.1.1. Simple configuration
Radvd's config file is normally /etc/radvd.conf. An simple example looks like
following:
interface eth0 {
AdvSendAdvert on;
MinRtrAdvInterval 3;
MaxRtrAdvInterval 10;
prefix 2001:0db8:0100:f101::/64 {
AdvOnLink on;
AdvAutonomous on;
AdvRouterAddr on;
};
};
This results on client side in
# ip -6 addr show eth0
3: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 100
inet6 2001:0db8:100:f101:2e0:12ff:fe34:1234/64 scope global dynamic
valid_lft 2591992sec preferred_lft 604792sec
inet6 fe80::2e0:12ff:fe34:1234/10 scope link
Because no lifetime was defined, a very high value was used.
4.1.2. Special 6to4 configuration
Version since 0.6.2pl3 support the automatic (re)-generation of the prefix
depending on an IPv4 address of a specified interface. This can be used to
distribute advertisements in a LAN after the 6to4 tunneling has changed. Mostly
used behind a dynamic dial-on-demand Linux router. Because of the sure shorter
lifetime of such prefix (after each dial-up, another prefix is valid), the
lifetime configured to minimal values:
interface eth0 {
AdvSendAdvert on;
MinRtrAdvInterval 3;
MaxRtrAdvInterval 10;
prefix 0:0:0:f101::/64 {
AdvOnLink off;
AdvAutonomous on;
AdvRouterAddr on;
Base6to4Interface ppp0;
AdvPreferredLifetime 20;
AdvValidLifetime 30;
};
};
This results on client side in (assuming, ppp0 has currently 1.2.3.4 as local
IPv4 address):
# /sbin/ip -6 addr show eth0
3: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 100
inet6 2002:0102:0304:f101:2e0:12ff:fe34:1234/64 scope global dynamic
valid_lft 22sec preferred_lft 12sec
inet6 fe80::2e0:12ff:fe34:1234/10 scope link
Because a small lifetime was defined, such prefix will be thrown away quickly,
if no related advertisement was received.
Additional note: if you do not used special 6to4 support in initscripts, you
have to setup a special route on the internal interface on the router,
otherwise you will get some backrouting problems. for the example showh here:
# /sbin/ip -6 route add 2002:0102:0304:f101::/64 dev eth0 metric 1
This route needs to be replaced every time the prefix changes, which is the
case after a new IPv4 address was assigned to the dial-up interface.
4.2. Debugging
A program called â€radvdump†can help you looking into sent or received
advertisements. Simple to use:
# radvdump
Router advertisement from fe80::280:c8ff:feb9:cef9 (hoplimit 255)
AdvCurHopLimit: 64
AdvManagedFlag: off
AdvOtherConfigFlag: off
AdvHomeAgentFlag: off
AdvReachableTime: 0
AdvRetransTimer: 0
Prefix 2002:0102:0304:f101::/64
AdvValidLifetime: 30
AdvPreferredLifetime: 20
AdvOnLink: off
AdvAutonomous: on
AdvRouterAddr: on
Prefix 2001:0db8:100:f101::/64
AdvValidLifetime: 2592000
AdvPreferredLifetime: 604800
AdvOnLink: on
AdvAutonomous: on
AdvRouterAddr: on
AdvSourceLLAddress: 00 80 12 34 56 78
Output shows you each advertisement package in readable format. You should see
your configured values here again, if not, perhaps it's not your radvd which
sends the advertisement...look for another router on the link (and take the
LLAddress, which is the MAC address for tracing).
5. Dynamic Host Configuration v6 Server (dhcp6s)
DHCPv6 can be used for stateful configurations. The daemon itself need not
necessary run on the Linux default IPv6 gateway router.
You can specify more information than by using radvd. The are most similar to
IPv4 DHCP server.
After a proper configuration, the daemon reacts on received ICMPv6 multicast
packets sent by a client to address ff02::1:2
5.1. Configuration of the DHCPv6 server (dhcp6s)
5.1.1. Simple configuration
dhcp6s's config file is normally /etc/dhcp6s.conf. An simple example looks like
following:
interface eth0 {
server-preference 255;
renew-time 60;
rebind-time 90;
prefer-life-time 130;
valid-life-time 200;
allow rapid-commit;
option dns_servers 2001:db8:0:f101::1 sub.domain.example;
link AAA {
range 2001:db8:0:f101::1000 to 2001:db8:0:f101::ffff/64;
prefix 2001:db8:0:f101::/64;
};
};
5.2. Configuration of the DHCPv6 client (dhcp6c)
5.2.1. Simple configuration
dhcp6c's config file is normally /etc/dhcp6c.conf. An simple example looks like
following:
interface eth0 {
send rapid-commit;
request domain-name-servers;
};
5.3. Usage
5.3.1. dhcpv6_server
Start server, e.g.
# service dhcp6s start
5.3.2. dhcpv6_client
Start client in foreground, e.g.
# dhcp6c -f eth0
5.4. Debugging
5.4.1. dhcpv6_server
The server has one foreground and two debug toggles (both should be used for
debugging), here is an example:
# dhcp6s -d -D -f eth0
5.4.2. dhcpv6_client
As general debugging for test whether the IPv6 DHCP server is reable on the
link use an IPv6 ping to the DHCP multicast address:
# ping6 -I eth0 ff02::1:2
The client has one foreground and two debug toggles, here is an example:
# dhcp6c -d -f eth0
Oct/03/2005 17:18:16 dhcpv6 doesn't support hardware type 776
Oct/03/2005 17:18:16 doesn't support sit0 address family 0
Oct/03/2005 17:18:16 netlink_recv_rtgenmsg error
Oct/03/2005 17:18:16 netlink_recv_rtgenmsg error
Oct/03/2005 17:18:17 status code for this address is: success
Oct/03/2005 17:18:17 status code: success
Oct/03/2005 17:18:17 netlink_recv_rtgenmsg error
Oct/03/2005 17:18:17 netlink_recv_rtgenmsg error
Oct/03/2005 17:18:17 assigned address 2001:db8:0:f101::1002 prefix len is not
¬ in any RAs prefix length using 64 bit instead
Oct/03/2005 17:18:17 renew time 60, rebind time 9
Note that the netlink error messages have no impact.
6. ISC Dynamic Host Configuration Server (dhcpd)
ISC DHCP supports IPv6 since version 4.x.
6.1. Configuration of the ISC DHCP server for IPv6 (dhcpd)
Note that currently, the ISC DHCP server can only serve IPv4 or IPv6, means you
have to start the daemon twice (for IPv6 with option â€-6â€) to support both
protocols.
6.1.1. Simple configuration
Create a dedicated configuration file /etc/dhcp/dhcpd6.conf for the IPv6 part
of the dhcpd. Note, that the router requires to have a interface configured
with an IPv6 address out of the defined subnet.
default-lease-time 600;
max-lease-time 7200;
log-facility local7;
subnet6 2001:db8:0:1::/64 {
# Range for clients
range6 2001:db8:0:1::129 2001:db8:0:1::254;
# Range for clients requesting a temporary address
range6 2001:db8:0:1::/64 temporary;
# Additional options
option dhcp6.name-servers fec0:0:0:1::1;
option dhcp6.domain-search "domain.example";
# Prefix range for delegation to sub-routers
prefix6 2001:db8:0:100:: 2001:db8:0:f00:: /56;
# Example for a fixed host address
host specialclient {
host-identifier option dhcp6.client-id 00:01:00:01:4a:1f:ba:e3:60:b9:
1f:01:23:45;
fixed-address6 2001:db8:0:1::127;
}
}
Note that the â€dhcp.client-id†no longer belongs to a MAC address, an unique ID
is used instead! â€dhcp6c†(see above) uses the file /var/lib/dhcpv6/dhcp6c_duid
(would be created during first start, if not existing) as unique identity. It's
a 14 byte long identifier, starting with a 2 byte length information (usually
â€0x000eâ€):
# hexdump -e '"%07.7_ax " 1/2 "%04x" " " 14/1 "%02x:" "\n"' /var/lib/dhcpv6/
dhcp6c_duid 0000000 000e 00:01:00:01:4a:1f:ba:e3:60:b9:1f:01:23:45:
6.2. Usage
6.2.1. dhcpd
Start server in foreground:
# /usr/sbin/dhcpd -6 -d -cf /etc/dhcp/dhcpd6.conf eth1
Internet Systems Consortium DHCP Server 4.1.0
Copyright 2004-2008 Internet Systems Consortium.
All rights reserved.
For info, please visit http://www.isc.org/sw/dhcp/
Not searching LDAP since ldap-server, ldap-port and ldap-base-dn were not
specified in the config file
Wrote 0 leases to leases file.
Bound to *:547
Listening on Socket/5/eth1/2001:db8:0:1::/64
Sending on Socket/5/eth1/2001:db8:0:1::/64
7. DHCP Server Dibbler
Dibbler is also a DHCP server
7.1. Configuration of the Dibbler DHCP server for IPv6
7.1.1. Simple configuration
Create a dedicated configuration file /etc/dibbler/server.conf . Note, that the
router requires to have a interface configured with an IPv6 address out of the
defined subnet.
log-level 8
log-mode short
preference 0
iface "eth1" {
// also ranges can be defines, instead of exact values t1 1800-2000 t2
2700-3000
prefered-lifetime 3600
valid-lifetime 7200
class {
pool 2001:6f8:12d8:1::/64
}
option dns-server fec0:0:0:1::1
option domain domain.example
}
7.2. Usage
7.2.1. dibbler-server
Start server in foreground:
# dibbler-server run
| Dibbler - a portable DHCPv6, version 0.7.3 (SERVER, Linux port)
| Authors : Tomasz Mrugalski<thomson(at)klub.com.pl>,Marek Senderski<msend
(at)o2.pl>
| Licence : GNU GPL v2 only. Developed at Gdansk University of Technology.
| Homepage: http://klub.com.pl/dhcpv6/
2009.05.28 10:18:48 Server Notice My pid (1789) is stored in /var/lib/
dibbler/server.pid
2009.05.28 10:18:48 Server Notice Detected iface eth0/3, MAC=54:52:00:01:
23:45.
2009.05.28 10:18:48 Server Notice Detected iface eth1/2, MAC=54:52:00:67:
89:ab.
2009.05.28 10:18:48 Server Notice Detected iface lo/1, MAC=00:00:00:00:00:
00.
2009.05.28 10:18:48 Server Debug Skipping database loading.
2009.05.28 10:18:48 Server Debug Cache:server-cache.xml file: parsing
started, expecting 0 entries.
2009.05.28 10:18:48 Server Notice Parsing /etc/dibbler/server.conf config
file...
18:48 Server Debug Setting 0 generic option(s).
18:48 Server Debug 0 per-client configurations (exceptions) added.
18:48 Server Debug Parsing /etc/dibbler/server.conf done.
18:48 Server Info 0 client class(es) defined.
18:48 Server Debug 1 interface(s) specified in /etc/dibbler/server.conf
18:48 Server Info Mapping allow, deny list to class 0:0 allow/deny
entries in total.
18:48 Server Info Interface eth1/2 configuration has been loaded.
18:48 Server Notice Running in stateful mode.
18:48 Server Info My DUID is 00:01:00:01:11:aa:6d:a7:54:52:00:67:89:ab.
18:48 Server Notice Creating multicast (ff02::1:2) socket on eth1/2 (eth1/
2) interface.
18:48 Server Debug Cache: size set to 1048576 bytes, 1 cache entry size
is 87 bytes, so maximum 12052 address-client pair(s) may be cached.
18:48 Server Notice Accepting connections. Next event in 4294967295 second
(s).
8. tcp_wrapper
tcp_wrapper is a library which can help you to protect service against misuse.
8.1. Filtering capabilities
You can use tcp_wrapper for
* Filtering against source addresses (IPv4 or IPv6)
* Filtering against users (requires a running ident daemon on the client)
8.2. Which program uses tcp_wrapper
Following are known:
* Each service which is called by xinetd (if xinetd is compiled using
tcp_wrapper library)
* sshd (if compiled using tcp_wrapper)
8.3. Usage
tcp_wrapper is controlled by two files name /etc/hosts.allow and /etc/
hosts.deny. For more information see
$ man hosts.allow
8.3.1. Example for /etc/hosts.allow
In this file, each service which should be positive filtered (means connects
are accepted) need a line.
sshd: 1.2.3. [2001:0db8:100:200::]/64
daytime-stream: 1.2.3. [2001:0db8:100:200::]/64
Note: there are broken implementations around, which uses following broken IPv6
network description: [2001:0db8:100:200::/64]. Hopefully, such versions will be
fixed soon.
8.3.2. Example for /etc/hosts.deny
This file contains all negative filter entries and should normally deny the
rest using
ALL: ALL
If this node is a more sensible one you can replace the standard line above
with this one, but this can cause a DoS attack (load of mailer and spool
directory), if too many connects were made in short time. Perhaps a logwatch is
better for such issues.
ALL: ALL: spawn (echo "Attempt from %h %a to %d at `date`"
| tee -a /var/log/tcp.deny.log | mail root@localhost)
8.4. Logging
Depending on the entry in the syslog daemon configuration file /etc/syslog.conf
the tcp_wrapper logs normally into /var/log/secure.
8.4.1. Refused connection
A refused connection via IPv4 to an xinetd covered daytime service produces a
line like following example
Jan 2 20:40:44 gate xinetd-ipv6[12346]: FAIL: daytime-stream libwrap
¬ from=::ffff:1.2.3.4
Jan 2 20:32:06 gate xinetd-ipv6[12346]: FAIL: daytime-stream libwrap
from=2001:0db8:100:200::212:34ff:fe12:3456
A refused connection via IPv4 to an dual-listen sshd produces a line like
following example
Jan 2 20:24:17 gate sshd[12345]: refused connect from ::ffff:1.2.3.4
¬ (::ffff:1.2.3.4)
Jan 2 20:39:33 gate sshd[12345]: refused connect
from 2001:0db8:100:200::212:34ff:fe12:3456
¬ (2001:0db8:100:200::212:34ff:fe12:3456)
8.4.2. Permitted connection
A permitted connection via IPv4 to an xinetd covered daytime service produces a
line like following example
Jan 2 20:37:50 gate xinetd-ipv6[12346]: START: daytime-stream pid=0
¬ from=::ffff:1.2.3.4
Jan 2 20:37:56 gate xinetd-ipv6[12346]: START: daytime-stream pid=0
from=2001:0db8:100:200::212:34ff:fe12:3456
A permitted connection via IPv4 to an dual-listen sshd produces a line like
following example
Jan 2 20:43:10 gate sshd[21975]: Accepted password for user from ::ffff:
1.2.3.4
¬ port 33381 ssh2
Jan 2 20:42:19 gate sshd[12345]: Accepted password for user
from 2001:0db8:100:200::212:34ff:fe12:3456 port 33380 ssh2
9. vsftpd
9.1. Listening on IPv6 addresses
Edit the configuration file, ususally /etc/vsftpd/vsftpd.conf, and adjust the
listen option like
listen_ipv6=yes
That's all.
10. proftpd
10.1. Listening on IPv6 addresses
Edit the configuration file, ususally /etc/proftpd.conf, but take care, not
100% logical in virtual host setup
<VirtualHost 192.0.2.1>
...
Bind 2001:0DB8::1
...
</VirtualHost>
That's all.
11. Other daemons
Nowadays it's mostly simple, look for either a command line option or a
configuration value to enable IPv6 listening. See manual page of the daemon or
check related FAQs. It can happen that you can bind a daemon only to the IPv6-
â€anyâ€-address (::) and not to bind to a dedicated IPv6 address, because the
lack of support (depends on that what the programmer has implemented so
far...).
Chapter 23. Programming
Table of Contents
1._Programming_using_C-API
1.1._Address_Structures
1.2._Lookup_Functions
1.3._Quirks_Encountered
1.4._Putting_It_All_Together_(A_Client-Server_Programming_Example)
2._Other_programming_languages
2.1._JAVA
2.2._Perl
1. Programming using C-API
Related RFCs:
* RFC_3493_/_Basic_Socket_Interface_Extensions_for_IPv6
* RFC_3542_/_Advanced_Sockets_Application_Program_Interface_(API)_for_IPv6
Following contents of this section is contributed by John Wenker, Sr. Software
Engineer Performance Technologies San Diego, CA USA http://www.pt.com/.
This section describes how to write IPv6 client-server applications under the
Linux operating system. First thing's first, and credit must be given where it
is due. The information contained in this section is derived from Chapters 2
through 4 of IPv6 Network Programming by Jun-ichiro itojun Hagino (ISBN 1-
55558-318-0). The reader is encouraged to consult that book for more detailed
information. It describes how to convert IPv4 applications to be IPv6
compatible in a protocol-independent way, and describes some of the common
problems encountered during the conversion along with suggested solutions. At
the time of this writing, this is the only book of which the author is aware
that specifically addresses how to program IPv6 applications [since writing
this section, the author has also become aware of the Porting applications to
IPv6 HowTo by Eva M. Castro at http://jungla.dit.upm.es/~ecastro/IPv6-web/
ipv6.html]. Unfortunately, of the almost 360 pages in the book, maybe 60 are
actually useful (the chapters mentioned). Nevertheless, without the guidance of
that book, the author would have been unable to perform his job duties or
compose this HowTo. While most (but certainly not all) of the information in
the Hagino book is available via the Linux 'man' pages, application programmers
will save a significant amount of time and frustration by reading the indicated
chapters of the book rather than searching through the 'man' pages and online
documentation.
Other than the Hagino book, any other information presented in this HowTo was
obtained through trial and error. Some items or explanations may not be
entirely â€correct†in the grand IPv6 scheme, but seem to work in practical
application.
The discussion that follows assumes the reader is already experienced with the
traditional TCP/IP socket API. For more information on traditional socket
programming, the Internetworking with TCP/IP series of textbooks by Comer &
Stevens is hard to beat, specifically Volume III: Client-Server Programming and
Applications, Linux/POSIX Sockets Version (ISBN 0-13-032071-4). This HowTo also
assumes that the reader has had at least a bare basic introduction to IPv6 and
in particular the addressing scheme for network addresses (see Section 2.3).
1.1. Address Structures
This section provides a brief overview of the structures provided in the socket
API to represent network addresses (or more specifically transport endpoints)
when using the Internet protocols in a client-server application.
1.1.1. IPv4 sockaddr_in
In IPv4, network addresses are 32 bits long and define a network node.
Addresses are written in dotted decimal notation, such as 192.0.2.1, where each
number represents eight bits of the address. Such an IPv4 address is
represented by the struct sockaddr_in data type, which is defined in <netinet/
in.h>.
struct sockaddr_in
{
sa_family_t sin_family;
in_port_t sin_port;
struct in_addr sin_addr;
/* Plus some padding for alignment */
};
The sin_family component indicates the address family. For IPv4 addresses, this
is always set to AF_INET. The sin_addr field contains the 32-bit network
address (in network byte order). Finally, the sin_port component represents the
transport layer port number (in network byte order). Readers should already be
familiar with this structure, as this is the standard IPv4 address structure.
1.1.2. IPv6 sockaddr_in6
The biggest feature of IPv6 is its increased address space. Instead of 32-bit
network addresses, IPv6 allots 128 bits to an address. Addresses are written in
colon-hex notation of the form fe80::2c0:8cff:fe01:2345, where each hex number
separated by colons represents 16 bits of the address. Two consecutive colons
indicate a string of consecutive zeros for brevity, and at most only one
double-colon may appear in the address. IPv6 addresses are represented by the
struct sockaddr_in6 data type, also defined in <netinet/in.h>.
struct sockaddr_in6
{
sa_family_t sin6_family;
in_port_t sin6_port;
uint32_t sin6_flowinfo;
struct in6_addr sin6_addr;
uint32_t sin6_scope_id;
};
The sin6_family, sin6_port, and sin6_addr components of the structure have the
same meaning as the corresponding fields in the sockaddr_in structure. However,
the sin6_family member is set to AF_INET6 for IPv6 addresses, and the sin6_addr
field holds a 128-bit address instead of only 32 bits.
The sin6_flowinfo field is used for flow control, but is not yet standardized
and can be ignored.
The sin6_scope_id field has an odd use, and it seems (at least to this naïve
author) that the IPv6 designers took a huge step backwards when devising this.
Apparently, 128-bit IPv6 network addresses are not unique. For example, it is
possible to have two hosts, on separate networks, with the same link-local
address (see Figure 1). In order to pass information to a specific host, more
than just the network address is required; the scope identifier must also be
specified. In Linux, the network interface name is used for the scope
identifier (e.g. â€eth0â€) [be warned that the scope identifier is implementation
dependent!]. Use the ifconfig(1M) command to display a list of active network
interfaces.
A colon-hex network address can be augmented with the scope identifier to
produce a "scoped addressâ€. The percent sign ('%') is used to delimit the
network address from the scope identifier. For example, fe80::1%eth0 is a
scoped IPv6 address where fe80::1 represents the 128-bit network address and
eth0 is the network interface (i.e. the scope identifier). Thus, if a host
resides on two networks, such as Host B in example below, the user now has to
know which path to take in order to get to a particular host. In Figure 1, Host
B addresses Host A using the scoped address fe80::1%eth0, while Host C is
addressed with fe80::1%eth1.
Host A (fe80::1) ---- eth0 ---- Host B ---- eth1 ---- Host C (fe80::1)
Getting back to the sockaddr_in6 structure, its sin6_scope_id field contains
the index of the network interface on which a host may be found. Server
applications will have this field set automatically by the socket API when they
accept a connection or receive a datagram. For client applications, if a scoped
address is passed as the node parameter to getaddrinfo(3) (described later in
this HowTo), then the sin6_scope_id field will be filled in correctly by the
system upon return from the function; if a scoped address is not supplied, then
the sin6_scope_id field must be explicitly set by the client software prior to
attempting to communicate with the remote server. The if_nametoindex(3)
function is used to translate a network interface name into its corresponding
index. It is declared in <net/if.h>.
1.1.3. Generic Addresses
As any programmer familiar with the traditional TCP/IP socket API knows,
several socket functions deal with "generic" pointers. For example, a pointer
to a generic struct sockaddr data type is passed as a parameter to some socket
functions (such as connect(2) or bind(2)) rather than a pointer to a specific
address type. Be careful… the sockaddr_in6 structure is larger than the generic
sockaddr structure! Thus, if your program receives a generic address whose
actual type is unknown (e.g. it could be an IPv4 address structure or an IPv6
address structure), you must supply sufficient storage to hold the entire
address. The struct sockaddr_storage data type is defined in <bits/socket.h>
for this purpose [do not #include this file directly within an application; use
<sys/socket.h> as usual, and <bits/socket.h> will be implicitly included].
For example, consider the recvfrom(2) system call, which is used to receive a
message from a remote peer. Its function prototype is:
ssize_t recvfrom( int s,
void *buf,
size_t len,
int flags,
struct sockaddr *from,
socklen_t *fromlen );
The from parameter points to a generic sockaddr structure. If data can be
received from an IPv6 peer on the socket referenced by s, then from should
point to a data type of struct sockaddr_storage, as in the following dummy
example:
/*
** Read a message from a remote peer, and return a buffer pointer to
** the caller.
**
** 's' is the file descriptor for the socket.
*/
char *rcvMsg( int s )
{
static char bfr[ 1025 ]; /* Where the msg is stored. */
ssize_t count;
struct sockaddr_storage ss; /* Where the peer adr goes. */
socklen_t sslen;
sslen = sizeof( ss );
count = recvfrom( s,
bfr,
sizeof( bfr ) - 1,
0,
(struct sockaddr*) &ss,
&sslen );
bfr[ count ] = '\0'; /* Null-terminates the message. */
return bfr;
} /* End rcvMsg() */
As seen in the above example, ss (a struct sockaddr_storage data object) is
used to receive the peer address information, but it's address is typecast to a
generic struct sockaddr* pointer in the call to recvfrom(2).
1.2. Lookup Functions
Traditionally, hostname and service name resolution were performed by functions
such as gethostbyname(3) and getservbyname(3). These traditional lookup
functions are still available, but they are not forward compatible to IPv6.
Instead, the IPv6 socket API provides new lookup functions that consolidate the
functionality of several traditional functions. These new lookup functions are
also backward compatible with IPv4, so a programmer can use the same
translation algorithm in an application for both the IPv4 and IPv6 protocols.
This is an important feature, because obviously a global IPv6 infrastructure
isn't going to be put in place overnight. Thus, during the transition period
from IPv4 to IPv6, client-server applications should be designed with the
flexibility to handle both protocols simultaneously. The example programs at
the end of this chapter do just that.
The primary lookup function in the new socket API is getaddrinfo(3). Its
prototype is as follows.
int getaddrinfo( const char *node,
const char *service,
const struct addrinfo *hints,
struct addrinfo **res );
The node parameter is a pointer to the hostname or IP address being translated.
The referenced string can be a hostname, IPv4 dotted decimal address, or IPv6
colon-hex address (possibly scoped). The service parameter is a pointer to the
transport layer's service name or port number. It can be specified as a name
found in /etc/services or a decimal number. getaddrinfo(3) resolves the host/
service combination and returns a list of address records; a pointer to the
list is placed in the location pointed at by res. For example, suppose a host
can be identified by both an IPv4 and IPv6 address, and that the indicated
service has both a TCP entry and UDP entry in /etc/services. In such a
scenario, it is not inconceivable that four address records are returned; one
for TCP/IPv6, one for UDP/IPv6, one for TCP/IPv4, and one for UDP/IPv4.
The definition for struct addrinfo is found in <netdb.h> (as is the declaration
for getaddrinfo(3) and the other functions described in this section). The
structure has the following format:
struct addrinfo
{
int ai_flags;
int ai_family;
int ai_socktype;
int ai_protocol;
socklen_t ai_addrlen;
struct sockaddr *ai_addr;
char *ai_canonname;
struct addrinfo *ai_next;
};
Consult the 'man' page for getaddrinfo(3) for detailed information about the
various fields; this HowTo only describes a subset of them, and only to the
extent necessary for normal IPv6 programming.
The ai_family, ai_socktype, and ai_protocol fields have the exact same meaning
as the parameters to the socket(2) system call. The ai_family field indicates
the protocol family (not the address family) associated with the record, and
will be PF_INET6 for IPv6 or PF_INET for IPv4. The ai_socktype parameter
indicates the type of socket to which the record corresponds; SOCK_STREAM for a
reliable connection-oriented byte-stream or SOCK_DGRAM for connectionless
communication. The ai_protocol field specifies the underlying transport
protocol for the record.
The ai_addr field points to a generic struct sockaddr object. Depending on the
value in the ai_family field, it will point to either a struct sockaddr_in
(PF_INET) or a struct sockaddr_in6 (PF_INET6). The ai_addrlen field contains
the size of the object pointed at by the ai_addr field.
As mentioned, getaddrinfo(3) returns a list of address records. The ai_next
field points to the next record in the list.
The hints parameter to getaddrinfo(3) is also of type struct addrinfo and acts
as a filter for the address records returned in res. If hints is NULL, all
matching records are returned; but if hints is non-NULL, the referenced
structure gives "hints" to getaddrinfo(3) about which records to return. Only
the ai_flags, ai_family, ai_socktype, and ai_protocol fields are significant in
the hints structure, and all other fields should be set to zero.
Programs can use hints->ai_family to specify the protocol family. For example,
if it is set to PF_INET6, then only IPv6 address records are returned.
Likewise, setting hints->ai_family to PF_INET results in only IPv4 address
records being returned. If an application wants both IPv4 and IPv6 records, the
field should be set to PF_UNSPEC.
The hints->socktype field can be set to SOCK_STREAM to return only records that
correspond to connection-oriented byte streams, SOCK_DGRAM to return only
records corresponding to connectionless communication, or 0 to return both.
For the Internet protocols, there is only one protocol associated with
connection-oriented sockets (TCP) and one protocol associated with
connectionless sockets (UDP), so setting hints->ai_socktype to SOCK_STREAM or
SOCK_DGRAM is the same as saying, "Give me only TCP records," or "Give me only
UDP records," respectively. With that in mind, the hints->ai_protocol field
isn't really that important with the Internet protocols, and pretty much
mirrors the hints->ai_socktype field. Nevertheless, hints->ai_protocol can be
set to IPPROTO_TCP to return only TCP records, IPPROTO_UDP to return only UDP
records, or 0 for both.
The node or service parameter to gethostbyname(3) can be NULL, but not both. If
node is NULL, then the ai_flags field of the hints parameter specifies how the
network address in a returned record is set (i.e. the sin_addr or sin6_addr
field of the object pointed at by the ai_addr component in a returned record).
If the AI_PASSIVE flag is set in hints, then the returned network addresses are
left unresolved (all zeros). This is how server applications would use
getaddrinfo(3). If the flag is not set, then the address is set to the local
loopback address (::1 for IPv6 or 127.0.0.1 for IPv4). This is one way a client
application can specify that the target server is running on the same machine
as the client. If the service parameter is NULL, the port number in the
returned address records remains unresolved.
The getaddrinfo(3) function returns zero on success, or an error code. In the
case of an error, the gai_strerror(3) function is used to obtain a character
pointer to an error message corresponding to the error code, just like strerror
(3) does in the standard 'C' library.
Once the address list is no longer needed, it must be freed by the application.
This is done with the freeaddrinfo(3) function.
The last function that will be mentioned in this section is getnameinfo(3).
This function is the inverse of getaddrinfo(3); it is used to create a string
representation of the hostname and service from a generic struct sockaddr data
object. It has the following prototype.
int getnameinfo( const struct sockaddr *sa,
socklen_t salen,
char *host,
size_t hostlen,
char *serv,
size_t servlen,
int flags );
The sa parameter points to the address structure in question, and salen
contains its size. The host parameter points to a buffer where the null-
terminated hostname string is placed, and the hostlen parameter is the size of
that buffer. If there is no hostname that corresponds to the address, then the
network address (dotted decimal or colon-hex) is placed in host. Likewise, the
serv parameter points to a buffer where the null-terminated service name string
(or port number) is placed, and the servlen parameter is the size of that
buffer. The flags parameter modifies the function's behavior; in particular,
the NI_NUMERICHOST flag indicates that the converted hostname should always be
formatted in numeric form (i.e. dotted decimal or colon-hex), and the
NI_NUMERICSERV flag indicates that the converted service should always be in
numeric form (i.e. the port number).
The symbols NI_MAXHOST and NI_MAXSERV are available to applications and
represent the maximum size of any converted hostname or service name,
respectively. Use these when declaring output buffers for getnameinfo(3).
1.3. Quirks Encountered
Before jumping into the programming examples, there are several quirks in IPv6
of which the reader should be aware. The more significant ones (in addition to
the non-uniqueness of IPv6 network addresses already discussed) are described
in the paragraphs below.
1.3.1. IPv4 Mapped Addresses
For security reasons that this author won't pretend to understand, "IPv4 mapped
addresses" should not be allowed in IPv6-capable server applications. To put it
in terms that everyone can understand, this simply means that a server should
not accept IPv4 traffic on an IPv6 socket (an otherwise legal operation). An
IPv4 mapped address is a mixed-format address of the form:
::ffff:192.0.2.1
where the first portion is in IPv6 colon-hex format and the last portion is in
IPv4 dotted decimal notation. The dotted decimal IPv4 address is the actual
network address, but it is being mapped into an IPv6 compatible format.
To prevent IPv4 mapped addresses from being accepted on an IPv6 socket, server
applications must explicitly set the IPV6_V6ONLY socket option on all IPv6
sockets created [the Hagino book implies that this is only a concern with
server applications. However, it has been observed during testing that if a
client application uses an IPv4 mapped address to specify the target server,
and the target server has IPv4 mapped addresses disabled, the connection still
completes regardless. On the server side, the connection endpoint is an IPv4
socket as desired; but on the client side, the connection endpoint is an IPv6
socket. Setting the IPV6_V6ONLY socket option on the client side as well as the
server side prevents any connection from being established at all.]. There's
only one problem. Apparently, IPV6_V6ONLY isn't defined on all systems [or at
least it wasn't in 2005 when the Hagino book was written]. The server example
at the end of this chapter provides a method for handling this problem.
If IPv4 traffic cannot be handled on IPv6 sockets, then that implies that
server applications must open both an IPv4 and IPv6 socket for a particular
network service if it wants to handle requests from either protocol. This goes
back to the flexibility issue mentioned earlier. If getaddrinfo(3) returns
multiple address records, then server applications should traverse the list and
open a passive socket for each address provided.
1.3.2. Cannot Specify the Scope Identifier in /etc/hosts
It is possible to assign a hostname to an IPv6 network address in /etc/hosts.
For example, the following is an excerpt from the /etc/hosts file on the
author's development system.
::1 localhost
127.0.0.1 localhost
fe80::2c0:8cff:fe01:2345 pt141
192.0.2.1 pt141
The "localhost" and "pt141" hostnames can be translated to either an IPv4 or
IPv6 network address. So, for example, if "pt141" is passed as the node
parameter to getaddrinfo(3), the function returns both an IPv4 and IPv6 address
record for the host (assuming the behavior hasn't been modified by the hints
parameter). Unfortunately, a scoped address cannot be used in /etc/hosts. Doing
so results in getaddrinfo(3) returning only the IPv4 record.
1.3.3. Client & Server Residing on the Same Machine
Suppose a machine has the IPv4 address 192.0.2.1. A client application running
on that machine can connect to a server application on the same machine by
using either the local loopback address (127.0.0.1) or the network address
(192.0.2.1) as the target server. Much to this author's surprise (and dismay),
it turns out that an IPv6 client application cannot connect to a server
application on the same machine if it uses the network address of that machine
as the target; it must use the local loopback address (::1).
1.4. Putting It All Together (A Client-Server Programming Example)
Now it's time to put everything discussed thus far together into a sample
client-server application. The remainder of this section is devoted to a remote
time-of-day application (the 'daytime' Internet service) [I noticed that Ms.
Castro used a 'daytime' example in her Porting applications to IPv6 HowTo. For
the record, the source code presented here is original, developed from scratch,
and any similarity between it and any other publicly available 'daytime'
example is purely coincidental.]. The source code presented in this section was
developed and tested on a RedHat Linux release using the 2.6 kernel (2.6.9 to
be specific). Readers may use the source code freely, so long as proper credit
is attributed; but of course the standard disclaimer must be given first:
Although the sample source code is believed to be free of errors, the
author makes no guarantees as to its reliability, especially
considering that some error paths were intentionally omitted for
brevity. Use it at your own risk!
When you get right down to it, there really aren't that many differences
between IPv4 and IPv6 applications. The trick is to code IPv6 applications in a
protocol-independent manner, such that they can handle both IPv4 and IPv6
simultaneously and transparently. This sample application does just that. The
only protocol-dependent code in the example occurs when printing network
addresses in verbose mode; but only after the ai_family field in the addrinfo
structure has been checked, so the programs know exactly what type of address
they're handling at the time.
1.4.1. 'Daytime' Server Code
The server code is found in file tod6d.c (time-of-day IPv6 daemon). Once built,
the server may be started using the following command syntax (assuming tod6d is
the executable file):
tod6d [-v] [service]
ARGUMENTS:
service
The service (or well-known port) on which to listen. Default is
"daytime".
OPTIONS:
-v
Turn on verbose mode.
The server handles both TCP and UDP requests on the network. The server source
code contained in tod6d.c follows:
/
******************************************************************************
* File: tod6d.c
* Description: Contains source code for an IPv6-capable 'daytime' server.
* Author: John Wenker, Sr. Software Engineer,
* Performance Technologies, San Diego, USA
******************************************************************************/
/*
** System header files.
*/
#include <errno.h> /* errno declaration & error codes.
*/
#include <netdb.h> /* getaddrinfo(3) et al. */
#include <netinet/in.h> /* sockaddr_in & sockaddr_in6 definition.
*/
#include <stdio.h> /* printf(3) et al. */
#include <stdlib.h> /* exit(2). */
#include <string.h> /* String manipulation & memory functions.
*/
#include <sys/poll.h> /* poll(2) and related definitions. */
#include <sys/socket.h> /* Socket functions (socket(2), bind(2), etc). */
#include <time.h> /* time(2) & ctime(3).
*/
#include <unistd.h> /* getopt(3), read(2), etc. */
/*
** Constants.
*/
#define DFLT_SERVICE "daytime" /* Default service name.
*/
#define INVALID_DESC -1 /* Invalid file descriptor.
*/
#define MAXCONNQLEN 3 /* Max nbr of connection requests to queue.
*/
#define MAXTCPSCKTS 2 /* One TCP socket for IPv4 & one for
IPv6. */
#define MAXUDPSCKTS 2 /* One UDP socket for IPv4 & one for
IPv6. */
#define VALIDOPTS "v" /* Valid command options.
*/
/*
** Simple boolean type definition.
*/
typedef enum { false = 0, true } boolean;
/*
** Prototypes for internal helper functions.
*/
static int openSckt( const char *service,
const char *protocol,
int desc[ ],
size_t *descSize );
static void tod( int tSckt[ ],
size_t tScktSize,
int uSckt[ ],
size_t uScktSize );
/*
** Global (within this file only) data objects.
*/
static char hostBfr[ NI_MAXHOST ]; /* For use w/getnameinfo(3).
*/
static const char *pgmName; /* Program name w/o dir prefix.
*/
static char servBfr[ NI_MAXSERV ]; /* For use w/getnameinfo(3).
*/
static boolean verbose = false; /* Verbose mode indication.
*/
/*
** Usage macro for command syntax violations.
*/
#define USAGE \
{ \
fprintf( stderr, \
"Usage: %s [-v] [service]\n", \
pgmName ); \
exit( 127 ); \
} /* End USAGE macro. */
/*
** Macro to terminate the program if a system call error occurs. The system
** call must be one of the usual type that returns -1 on error. This macro
is
** a modified version of a macro authored by Dr. V. Vinge, SDSU Dept. of
** Computer Science (retired)... best professor I ever had. I hear he writes
** great science fiction in addition to robust code, too.
*/
#define CHK(expr) \
do \
{ \
if ( (expr) == -1 ) \
{ \
fprintf( stderr, \
"%s (line %d): System call ERROR - %s.\n", \
pgmName, \
__LINE__, \
strerror( errno ) ); \
exit( 1 ); \
} /* End IF system call failed. */ \
} while ( false )
/
******************************************************************************
* Function: main
*
* Description:
* Set up a time-of-day server and handle network requests. This server
* handles both TCP and UDP requests.
*
* Parameters:
* The usual argc and argv parameters to a main() function.
*
* Return Value:
* This is a daemon program and never returns. However, in the degenerate
* case where no sockets are created, the function returns zero.
******************************************************************************/
int main( int argc,
char *argv[ ] )
{
int opt;
const char *service = DFLT_SERVICE;
int tSckt[ MAXTCPSCKTS ]; /* Array of TCP socket descriptors.
*/
size_t tScktSize = MAXTCPSCKTS; /* Size of uSckt (# of elements).
*/
int uSckt[ MAXUDPSCKTS ]; /* Array of UDP socket descriptors.
*/
size_t uScktSize = MAXUDPSCKTS; /* Size of uSckt (# of elements).
*/
/*
** Set the program name (w/o directory prefix).
*/
pgmName = strrchr( argv[ 0 ], '/' );
pgmName = pgmName == NULL ? argv[ 0 ] : pgmName + 1;
/*
** Process command options.
*/
opterr = 0; /* Turns off "invalid option" error messages. */
while ( ( opt = getopt( argc, argv, VALIDOPTS ) ) >= 0 )
{
switch ( opt )
{
case 'v': /* Verbose mode. */
{
verbose = true;
break;
}
default:
{
USAGE;
}
} /* End SWITCH on command option. */
} /* End WHILE processing options. */
/*
** Process command line arguments.
*/
switch ( argc - optind )
{
case 0: break;
case 1: service = argv[ optind ]; break;
default: USAGE;
} /* End SWITCH on number of command line arguments. */
/*
** Open both a TCP and UDP socket, for both IPv4 & IPv6, on which to
receive
** service requests.
*/
if ( ( openSckt( service, "tcp", tSckt, &tScktSize ) < 0 ) ||
( openSckt( service, "udp", uSckt, &uScktSize ) < 0 ) )
{
exit( 1 );
}
/*
** Run the time-of-day server.
*/
if ( ( tScktSize > 0 ) || ( uScktSize > 0 ) )
{
tod( tSckt, /* tod() never returns. */
tScktSize,
uSckt,
uScktSize );
}
/*
** Since tod() never returns, execution only gets here if no sockets were
** created.
*/
if ( verbose )
{
fprintf( stderr,
"%s: No sockets opened... terminating.\n",
pgmName );
}
return 0;
} /* End main() */
/
******************************************************************************
* Function: openSckt
*
* Description:
* Open passive (server) sockets for the indicated inet service &
protocol.
* Notice in the last sentence that "sockets" is plural. During the
interim
* transition period while everyone is switching over to IPv6, the server
* application has to open two sockets on which to listen for
connections...
* one for IPv4 traffic and one for IPv6 traffic.
*
* Parameters:
* service - Pointer to a character string representing the well-known
port
* on which to listen (can be a service name or a decimal
number).
* protocol - Pointer to a character string representing the transport
layer
* protocol (only "tcp" or "udp" are valid).
* desc - Pointer to an array into which the socket descriptors are
* placed when opened.
* descSize - This is a value-result parameter. On input, it contains the
* max number of descriptors that can be put into 'desc' (i.e.
the
* number of elements in the array). Upon return, it will
contain
* the number of descriptors actually opened. Any unused slots
in
* 'desc' are set to INVALID_DESC.
*
* Return Value:
* 0 on success, -1 on error.
******************************************************************************/
static int openSckt( const char *service,
const char *protocol,
int desc[ ],
size_t *descSize )
{
struct addrinfo *ai;
int aiErr;
struct addrinfo *aiHead;
struct addrinfo hints = { .ai_flags = AI_PASSIVE, /* Server mode.
¬ */
.ai_family = PF_UNSPEC }; /* IPv4 or IPv6.
¬ */
size_t maxDescs = *descSize;
/*
** Initialize output parameters. When the loop completes, *descSize is 0.
*/
while ( *descSize > 0 )
{
desc[ --( *descSize ) ] = INVALID_DESC;
}
/*
** Check which protocol is selected (only TCP and UDP are valid).
*/
if ( strcmp( protocol, "tcp" ) == 0 ) /* TCP protocol. */
{
hints.ai_socktype = SOCK_STREAM;
hints.ai_protocol = IPPROTO_TCP;
}
else if ( strcmp( protocol, "udp" ) == 0 ) /* UDP protocol. */
{
hints.ai_socktype = SOCK_DGRAM;
hints.ai_protocol = IPPROTO_UDP;
}
else /* Invalid protocol. */
{
fprintf( stderr,
"%s (line %d): ERROR - Unknown transport "
"layer protocol \"%s\".\n",
pgmName,
__LINE__,
protocol );
return -1;
}
/*
** Look up the service's well-known port number. Notice that NULL is
being
** passed for the 'node' parameter, and that the AI_PASSIVE flag is set in
** 'hints'. Thus, the program is requesting passive address information.
** The network address is initialized to :: (all zeros) for IPv6 records,
or
** 0.0.0.0 for IPv4 records.
*/
if ( ( aiErr = getaddrinfo( NULL,
service,
&hints,
&aiHead ) ) != 0 )
{
fprintf( stderr,
"%s (line %d): ERROR - %s.\n",
pgmName,
__LINE__,
gai_strerror( aiErr ) );
return -1;
}
/*
** For each of the address records returned, attempt to set up a passive
** socket.
*/
for ( ai = aiHead;
( ai != NULL ) && ( *descSize < maxDescs );
ai = ai->ai_next )
{
if ( verbose )
{
/*
** Display the current address info. Start with the protocol-
** independent fields first.
*/
fprintf( stderr,
"Setting up a passive socket based on the "
"following address info:\n"
" ai_flags = 0x%02X\n"
" ai_family = %d (PF_INET = %d, PF_INET6 = %d)\n"
" ai_socktype = %d (SOCK_STREAM = %d, SOCK_DGRAM =
%d)\n"
" ai_protocol = %d (IPPROTO_TCP = %d, IPPROTO_UDP =
%d)\n"
" ai_addrlen = %d (sockaddr_in = %d, "
"sockaddr_in6 = %d)\n",
ai->ai_flags,
ai->ai_family,
PF_INET,
PF_INET6,
ai->ai_socktype,
SOCK_STREAM,
SOCK_DGRAM,
ai->ai_protocol,
IPPROTO_TCP,
IPPROTO_UDP,
ai->ai_addrlen,
sizeof( struct sockaddr_in ),
sizeof( struct sockaddr_in6 ) );
/*
** Now display the protocol-specific formatted socket address. Note
** that the program is requesting that getnameinfo(3) convert the
** host & service into numeric strings.
*/
getnameinfo( ai->ai_addr,
ai->ai_addrlen,
hostBfr,
sizeof( hostBfr ),
servBfr,
sizeof( servBfr ),
NI_NUMERICHOST | NI_NUMERICSERV );
switch ( ai->ai_family )
{
case PF_INET: /* IPv4 address record. */
{
struct sockaddr_in *p = (struct sockaddr_in*) ai->ai_addr;
fprintf( stderr,
" ai_addr = sin_family: %d (AF_INET = %d, "
"AF_INET6 = %d)\n"
" sin_addr: %s\n"
" sin_port: %s\n",
p->sin_family,
AF_INET,
AF_INET6,
hostBfr,
servBfr );
break;
} /* End CASE of IPv4. */
case PF_INET6: /* IPv6 address record. */
{
struct sockaddr_in6 *p = (struct sockaddr_in6*) ai->ai_addr;
fprintf( stderr,
" ai_addr = sin6_family: %d (AF_INET = %d, "
"AF_INET6 = %d)\n"
" sin6_addr: %s\n"
" sin6_port: %s\n"
" sin6_flowinfo: %d\n"
" sin6_scope_id: %d\n",
p->sin6_family,
AF_INET,
AF_INET6,
hostBfr,
servBfr,
p->sin6_flowinfo,
p->sin6_scope_id );
break;
} /* End CASE of IPv6. */
default: /* Can never get here, but just for completeness. */
{
fprintf( stderr,
"%s (line %d): ERROR - Unknown protocol family
(%d).\n",
pgmName,
__LINE__,
ai->ai_family );
freeaddrinfo( aiHead );
return -1;
} /* End DEFAULT case (unknown protocol family). */
} /* End SWITCH on protocol family. */
} /* End IF verbose mode. */
/*
** Create a socket using the info in the addrinfo structure.
*/
CHK( desc[ *descSize ] = socket( ai->ai_family,
ai->ai_socktype,
ai->ai_protocol ) );
/*
** Here is the code that prevents "IPv4 mapped addresses", as discussed
** in Section 22.1.3.1. If an IPv6 socket was just created, then set
the
** IPV6_V6ONLY socket option.
*/
if ( ai->ai_family == PF_INET6 )
{
#if defined( IPV6_V6ONLY )
/*
** Disable IPv4 mapped addresses.
*/
int v6Only = 1;
CHK( setsockopt( desc[ *descSize ],
IPPROTO_IPV6,
IPV6_V6ONLY,
&v6Only,
sizeof( v6Only ) ) );
#else
/*
** IPV6_V6ONLY is not defined, so the socket option can't be set and
** thus IPv4 mapped addresses can't be disabled. Print a warning
** message and close the socket. Design note: If the
** #if...#else...#endif construct were removed, then this program
** would not compile (because IPV6_V6ONLY isn't defined). That's an
** acceptable approach; IPv4 mapped addresses are certainly disabled
** if the program can't build! However, since this program is also
** designed to work for IPv4 sockets as well as IPv6, I decided to
** allow the program to compile when IPV6_V6ONLY is not defined, and
** turn it into a run-time warning rather than a compile-time error.
** IPv4 mapped addresses are still disabled because _all_ IPv6
traffic
** is disabled (all IPv6 sockets are closed here), but at least this
** way the server can still service IPv4 network traffic.
*/
fprintf( stderr,
"%s (line %d): WARNING - Cannot set IPV6_V6ONLY socket "
"option. Closing IPv6 %s socket.\n",
pgmName,
__LINE__,
ai->ai_protocol == IPPROTO_TCP ? "TCP" : "UDP" );
CHK( close( desc[ *descSize ] ) );
continue; /* Go to top of FOR loop w/o updating *descSize! */
#endif /* IPV6_V6ONLY */
} /* End IF this is an IPv6 socket. */
/*
** Bind the socket. Again, the info from the addrinfo structure is
used.
*/
CHK( bind( desc[ *descSize ],
ai->ai_addr,
ai->ai_addrlen ) );
/*
** If this is a TCP socket, put the socket into passive listening mode
** (listen is only valid on connection-oriented sockets).
*/
if ( ai->ai_socktype == SOCK_STREAM )
{
CHK( listen( desc[ *descSize ],
MAXCONNQLEN ) );
}
/*
** Socket set up okay. Bump index to next descriptor array element.
*/
*descSize += 1;
} /* End FOR each address info structure returned. */
/*
** Dummy check for unused address records.
*/
if ( verbose && ( ai != NULL ) )
{
fprintf( stderr,
"%s (line %d): WARNING - Some address records were "
"not processed due to insufficient array space.\n",
pgmName,
__LINE__ );
} /* End IF verbose and some address records remain unprocessed. */
/*
** Clean up.
*/
freeaddrinfo( aiHead );
return 0;
} /* End openSckt() */
/
******************************************************************************
* Function: tod
*
* Description:
* Listen on a set of sockets and send the current time-of-day to any
* clients. This function never returns.
*
* Parameters:
* tSckt - Array of TCP socket descriptors on which to listen.
* tScktSize - Size of the tSckt array (nbr of elements).
* uSckt - Array of UDP socket descriptors on which to listen.
* uScktSize - Size of the uSckt array (nbr of elements).
*
* Return Value: None.
******************************************************************************/
static void tod( int tSckt[ ],
size_t tScktSize,
int uSckt[ ],
size_t uScktSize )
{
char bfr[ 256 ];
ssize_t count;
struct pollfd *desc;
size_t descSize = tScktSize + uScktSize;
int idx;
int newSckt;
struct sockaddr *sadr;
socklen_t sadrLen;
struct sockaddr_storage sockStor;
int status;
size_t timeLen;
char *timeStr;
time_t timeVal;
ssize_t wBytes;
/*
** Allocate memory for the poll(2) array.
*/
desc = malloc( descSize * sizeof( struct pollfd ) );
if ( desc == NULL )
{
fprintf( stderr,
"%s (line %d): ERROR - %s.\n",
pgmName,
__LINE__,
strerror( ENOMEM ) );
exit( 1 );
}
/*
** Initialize the poll(2) array.
*/
for ( idx = 0; idx < descSize; idx++ )
{
desc[ idx ].fd = idx < tScktSize ? tSckt[ idx ]
: uSckt[ idx - tScktSize ];
desc[ idx ].events = POLLIN;
desc[ idx ].revents = 0;
}
/*
** Main time-of-day server loop. Handles both TCP & UDP requests.
This is
** an interative server, and all requests are handled directly within the
** main loop.
*/
while ( true ) /* Do forever. */
{
/*
** Wait for activity on one of the sockets. The DO..WHILE construct is
** used to restart the system call in the event the process is
** interrupted by a signal.
*/
do
{
status = poll( desc,
descSize,
-1 /* Wait indefinitely for input. */ );
} while ( ( status < 0 ) && ( errno == EINTR ) );
CHK( status ); /* Check for a bona fide system call error. */
/*
** Get the current time.
*/
timeVal = time( NULL );
timeStr = ctime( &timeVal );
timeLen = strlen( timeStr );
/*
** Indicate that there is new network activity.
*/
if ( verbose )
{
char *s = malloc( timeLen+1 );
strcpy( s, timeStr );
s[ timeLen-1 ] = '\0'; /* Overwrite '\n' in date string. */
fprintf( stderr,
"%s: New network activity on %s.\n",
pgmName,
s );
free( s );
} /* End IF verbose. */
/*
** Process sockets with input available.
*/
for ( idx = 0; idx < descSize; idx++ )
{
switch ( desc[ idx ].revents )
{
case 0: /* No activity on this socket; try the next. */
continue;
case POLLIN: /* Network activity. Go process it. */
break;
default: /* Invalid poll events. */
{
fprintf( stderr,
"%s (line %d): ERROR - Invalid poll event
(0x%02X).\n",
pgmName,
__LINE__,
desc[ idx ].revents );
exit( 1 );
}
} /* End SWITCH on returned poll events. */
/*
** Determine if this is a TCP request or UDP request.
*/
if ( idx < tScktSize )
{
/*
** TCP connection requested. Accept it. Notice the use of
** the sockaddr_storage data type.
*/
sadrLen = sizeof( sockStor );
sadr = (struct sockaddr*) &sockStor;
CHK( newSckt = accept( desc[ idx ].fd,
sadr,
&sadrLen ) );
CHK( shutdown( newSckt, /* Server never recv's anything. */
SHUT_RD ) );
if ( verbose )
{
/*
** Display the socket address of the remote client. Begin
with
** the address-independent fields.
*/
fprintf( stderr,
"Sockaddr info for new TCP client:\n"
" sa_family = %d (AF_INET = %d, AF_INET6 = %d)\n"
" addr len = %d (sockaddr_in = %d, "
"sockaddr_in6 = %d)\n",
sadr->sa_family,
AF_INET,
AF_INET6,
sadrLen,
sizeof( struct sockaddr_in ),
sizeof( struct sockaddr_in6 ) );
/*
** Display the address-specific fields.
*/
getnameinfo( sadr,
sadrLen,
hostBfr,
sizeof( hostBfr ),
servBfr,
sizeof( servBfr ),
NI_NUMERICHOST | NI_NUMERICSERV );
/*
** Notice that we're switching on an address family now, not a
** protocol family.
*/
switch ( sadr->sa_family )
{
case AF_INET: /* IPv4 address. */
{
struct sockaddr_in *p = (struct sockaddr_in*) sadr;
fprintf( stderr,
" sin_addr = sin_family: %d\n"
" sin_addr: %s\n"
" sin_port: %s\n",
p->sin_family,
hostBfr,
servBfr );
break;
} /* End CASE of IPv4. */
case AF_INET6: /* IPv6 address. */
{
struct sockaddr_in6 *p = (struct sockaddr_in6*) sadr;
fprintf( stderr,
" sin6_addr = sin6_family: %d\n"
" sin6_addr: %s\n"
" sin6_port: %s\n"
" sin6_flowinfo: %d\n"
" sin6_scope_id: %d\n",
p->sin6_family,
hostBfr,
servBfr,
p->sin6_flowinfo,
p->sin6_scope_id );
break;
} /* End CASE of IPv6. */
default: /* Can never get here, but for completeness. */
{
fprintf( stderr,
"%s (line %d): ERROR - Unknown address "
"family (%d).\n",
pgmName,
__LINE__,
sadr->sa_family );
break;
} /* End DEFAULT case (unknown address family). */
} /* End SWITCH on address family. */
} /* End IF verbose mode. */
/*
** Send the TOD to the client.
*/
wBytes = timeLen;
while ( wBytes > 0 )
{
do
{
count = write( newSckt,
timeStr,
wBytes );
} while ( ( count < 0 ) && ( errno == EINTR ) );
CHK( count ); /* Check for a bona fide error. */
wBytes -= count;
} /* End WHILE there is data to send. */
CHK( close( newSckt ) );
} /* End IF this was a TCP connection request. */
else
{
/*
** This is a UDP socket, and a datagram is available. The funny
** thing about UDP requests is that this server doesn't require
any
** client input; but it can't send the TOD unless it knows a
client
** wants the data, and the only way that can occur with UDP is if
** the server receives a datagram from the client. Thus, the
** server must receive _something_, but the content of the
datagram
** is irrelevant. Read in the datagram. Again note the use of
** sockaddr_storage to receive the address.
*/
sadrLen = sizeof( sockStor );
sadr = (struct sockaddr*) &sockStor;
CHK( count = recvfrom( desc[ idx ].fd,
bfr,
sizeof( bfr ),
0,
sadr,
&sadrLen ) );
/*
** Display whatever was received on stdout.
*/
if ( verbose )
{
ssize_t rBytes = count;
fprintf( stderr,
"%s: UDP datagram received (%d bytes).\n",
pgmName,
count );
while ( count > 0 )
{
fputc( bfr[ rBytes - count-- ],
stdout );
}
if ( bfr[ rBytes-1 ] != '\n' )
fputc( '\n', stdout ); /* Newline also flushes stdout. */
/*
** Display the socket address of the remote client. Address-
** independent fields first.
*/
fprintf( stderr,
"Remote client's sockaddr info:\n"
" sa_family = %d (AF_INET = %d, AF_INET6 = %d)\n"
" addr len = %d (sockaddr_in = %d, "
"sockaddr_in6 = %d)\n",
sadr->sa_family,
AF_INET,
AF_INET6,
sadrLen,
sizeof( struct sockaddr_in ),
sizeof( struct sockaddr_in6 ) );
/*
** Display the address-specific information.
*/
getnameinfo( sadr,
sadrLen,
hostBfr,
sizeof( hostBfr ),
servBfr,
sizeof( servBfr ),
NI_NUMERICHOST | NI_NUMERICSERV );
switch ( sadr->sa_family )
{
case AF_INET: /* IPv4 address. */
{
struct sockaddr_in *p = (struct sockaddr_in*) sadr;
fprintf( stderr,
" sin_addr = sin_family: %d\n"
" sin_addr: %s\n"
" sin_port: %s\n",
p->sin_family,
hostBfr,
servBfr );
break;
} /* End CASE of IPv4 address. */
case AF_INET6: /* IPv6 address. */
{
struct sockaddr_in6 *p = (struct sockaddr_in6*) sadr;
fprintf( stderr,
" sin6_addr = sin6_family: %d\n"
" sin6_addr: %s\n"
" sin6_port: %s\n"
" sin6_flowinfo: %d\n"
" sin6_scope_id: %d\n",
p->sin6_family,
hostBfr,
servBfr,
p->sin6_flowinfo,
p->sin6_scope_id );
break;
} /* End CASE of IPv6 address. */
default: /* Can never get here, but for completeness. */
{
fprintf( stderr,
"%s (line %d): ERROR - Unknown address "
"family (%d).\n",
pgmName,
__LINE__,
sadr->sa_family );
break;
} /* End DEFAULT case (unknown address family). */
} /* End SWITCH on address family. */
} /* End IF verbose mode. */
/*
** Send the time-of-day to the client.
*/
wBytes = timeLen;
while ( wBytes > 0 )
{
do
{
count = sendto( desc[ idx ].fd,
timeStr,
wBytes,
0,
sadr, /* Address & address
length */
sadrLen ); /* received in recvfrom().
*/
} while ( ( count < 0 ) && ( errno == EINTR ) );
CHK( count ); /* Check for a bona fide error. */
wBytes -= count;
} /* End WHILE there is data to send. */
} /* End ELSE a UDP datagram is available. */
desc[ idx ].revents = 0; /* Clear the returned poll events. */
} /* End FOR each socket descriptor. */
} /* End WHILE forever. */
} /* End tod() */
1.4.2. 'Daytime' TCP Client Code
The TCP client code is found in file tod6tc.c (time-of-day IPv6 TCP client).
Once built, the TCP client may be started using the following command syntax
(assuming tod6tc is the executable file):
tod6tc [-v] [-s scope_id] [host [service]]
ARGUMENTS:
host
The hostname or IP address (dotted decimal or colon-hex) of the remote
host providing the service. Default is "localhost".
service
The TCP service (or well-known port number) to which a connection attempt
is made. Default is "daytime".
OPTIONS:
-s
This option is only meaningful for IPv6 addresses, and is used to set the
scope identifier (i.e. the network interface on which to establish the
connection). Default is "eth0". If host is a scoped address, this option
is ignored.
-v
Turn on verbose mode.
The TCP client source code contained in tod6tc.c follows:
/
******************************************************************************
* File: tod6tc.c
* Description: Contains source code for an IPv6-capable 'daytime' TCP client.
* Author: John Wenker, Sr. Software Engineer
* Performance Technologies, San Diego, USA
******************************************************************************/
/*
** System header files.
*/
#include <errno.h> /* errno declaration and error codes.
*/
#include <net/if.h> /* if_nametoindex(3).
*/
#include <netdb.h> /* getaddrinfo(3) and associated definitions.
*/
#include <netinet/in.h> /* sockaddr_in and sockaddr_in6 definitions.
*/
#include <stdio.h> /* printf(3) et al.
*/
#include <stdlib.h> /* exit(2).
*/
#include <string.h> /* String manipulation and memory functions.
*/
#include <sys/socket.h> /* Socket functions (socket(2), connect(2), etc).
*/
#include <unistd.h> /* getopt(3), read(2), etc.
*/
/*
** Constants & macros.
*/
#define DFLT_HOST "localhost" /* Default server name. */
#define DFLT_SCOPE_ID "eth0" /* Default scope identifier. */
#define DFLT_SERVICE "daytime" /* Default service name. */
#define INVALID_DESC -1 /* Invalid file (socket) descriptor. */
#define MAXBFRSIZE 256 /* Max bfr sz to read remote TOD. */
#define VALIDOPTS "s:v" /* Valid command options. */
/*
** Type definitions (for convenience).
*/
typedef enum { false = 0, true } boolean;
typedef struct sockaddr_in sockaddr_in_t;
typedef struct sockaddr_in6 sockaddr_in6_t;
/*
** Prototypes for internal helper functions.
*/
static int openSckt( const char *host,
const char *service,
unsigned int scopeId );
static void tod( int sckt );
/*
** Global (within this file only) data objects.
*/
static const char *pgmName; /* Program name (w/o directory). */
static boolean verbose = false; /* Verbose mode. */
/*
** Usage macro.
*/
#define USAGE \
{ \
fprintf( stderr, \
"Usage: %s [-v] [-s scope_id] [host [service]]\n", \
pgmName ); \
exit( 127 ); \
} /* End USAGE macro. */
/*
** This "macro" (even though it's really a function) is loosely based on the
** CHK() macro by Dr. V. Vinge (see server code). The status parameter is
** a boolean expression indicating the return code from one of the usual
system
** calls that returns -1 on error. If a system call error occurred, an alert
** is written to stderr. It returns a boolean value indicating success/
failure
** of the system call.
**
** Example: if ( !SYSCALL( "write",
** count = write( fd, bfr, size ) ) )
** {
** // Error processing... but SYSCALL() will have already taken
** // care of dumping an error alert to stderr.
** }
*/
static __inline boolean SYSCALL( const char *syscallName,
int lineNbr,
int status )
{
if ( ( status == -1 ) && verbose )
{
fprintf( stderr,
"%s (line %d): System call failed ('%s') - %s.\n",
pgmName,
lineNbr,
syscallName,
strerror( errno ) );
}
return status != -1; /* True if the system call was successful. */
} /* End SYSCALL() */
/
******************************************************************************
* Function: main
*
* Description:
* Connect to a remote time-of-day service and write the remote host's TOD
to
* stdout.
*
* Parameters:
* The usual argc & argv parameters to a main() program.
*
* Return Value:
* This function always returns zero.
******************************************************************************/
int main( int argc,
char *argv[ ] )
{
const char *host = DFLT_HOST;
int opt;
int sckt;
unsigned int scopeId = if_nametoindex( DFLT_SCOPE_ID );
const char *service = DFLT_SERVICE;
/*
** Determine the program name (w/o directory prefix).
*/
pgmName = (const char*) strrchr( argv[ 0 ], '/' );
pgmName = pgmName == NULL ? argv[ 0 ] : pgmName+1;
/*
** Process command line options.
*/
opterr = 0; /* Turns off "invalid option" error messages. */
while ( ( opt = getopt( argc, argv, VALIDOPTS ) ) != -1 )
{
switch ( opt )
{
case 's': /* Scope identifier (IPv6 kluge). */
{
scopeId = if_nametoindex( optarg );
if ( scopeId == 0 )
{
fprintf( stderr,
"%s: Unknown network interface (%s).\n",
pgmName,
optarg );
USAGE;
}
break;
}
case 'v': /* Verbose mode. */
{
verbose = true;
break;
}
default:
{
USAGE;
}
} /* End SWITCH on command option. */
} /* End WHILE processing command options. */
/*
** Process command arguments. At the end of the above loop, optind is the
** index of the first NON-option argv element.
*/
switch ( argc - optind )
{
case 2: /* Both host & service are specified on the command line.
*/
{
service = argv[ optind + 1 ];
/***** Fall through *****/
}
case 1: /* Host is specified on the command line. */
{
host = argv[ optind ];
/***** Fall through *****/
}
case 0: /* Use default host & service. */
{
break;
}
default:
{
USAGE;
}
} /* End SWITCH on number of command arguments. */
/*
** Open a connection to the indicated host/service.
**
** Note that if all three of the following conditions are met, then the
** scope identifier remains unresolved at this point.
** 1) The default network interface is unknown for some reason.
** 2) The -s option was not used on the command line.
** 3) An IPv6 "scoped address" was not specified for the hostname on
the
** command line.
** If the above three conditions are met, then only an IPv4 socket can be
** opened (connect(2) fails without the scope ID properly set for IPv6
** sockets).
*/
if ( ( sckt = openSckt( host,
service,
scopeId ) ) == INVALID_DESC )
{
fprintf( stderr,
"%s: Sorry... a connection could not be established.\n",
pgmName );
exit( 1 );
}
/*
** Get the remote time-of-day.
*/
tod( sckt );
/*
** Close the connection and terminate.
*/
(void) SYSCALL( "close",
__LINE__,
close( sckt ) );
return 0;
} /* End main() */
/
******************************************************************************
* Function: openSckt
*
* Description:
* Sets up a TCP connection to a remote server. Getaddrinfo(3) is used to
* perform lookup functions and can return multiple address records (i.e. a
* list of 'struct addrinfo' records). This function traverses the list
and
* tries to establish a connection to the remote server. The function ends
* when either a connection has been established or all records in the list
* have been processed.
*
* Parameters:
* host - A pointer to a character string representing the hostname or
IP
* address (IPv4 or IPv6) of the remote server.
* service - A pointer to a character string representing the service name
or
* well-known port number.
* scopeId - For IPv6 sockets only. This is the index corresponding to the
* network interface on which to set up the connection. This
* parameter is ignored for IPv4 sockets or when an IPv6 "scoped
* address" is specified in 'host' (i.e. where the colon-hex
* network address is augmented with the scope ID).
*
* Return Value:
* Returns the socket descriptor for the connection, or INVALID_DESC if all
* address records have been processed and a connection could not be
* established.
******************************************************************************/
static int openSckt( const char *host,
const char *service,
unsigned int scopeId )
{
struct addrinfo *ai;
int aiErr;
struct addrinfo *aiHead;
struct addrinfo hints;
sockaddr_in6_t *pSadrIn6;
int sckt;
/*
** Initialize the 'hints' structure for getaddrinfo(3).
**
** Notice that the 'ai_family' field is set to PF_UNSPEC, indicating to
** return both IPv4 and IPv6 address records for the host/service. Most
of
** the time, the user isn't going to care whether an IPv4 connection or an
** IPv6 connection is established; the user simply wants to exchange data
** with the remote host and doesn't care how it's done. Sometimes,
however,
** the user might want to explicitly specify the type of underlying
socket.
** It is left as an exercise for the motivated reader to add a command
line
** option allowing the user to specify the IP protocol, and then process
the
** list of addresses accordingly (it's not that difficult).
*/
memset( &hints, 0, sizeof( hints ) );
hints.ai_family = PF_UNSPEC; /* IPv4 or IPv6 records (don't care).
*/
hints.ai_socktype = SOCK_STREAM; /* Connection-oriented byte stream.
*/
hints.ai_protocol = IPPROTO_TCP; /* TCP transport layer protocol only.
*/
/*
** Look up the host/service information.
*/
if ( ( aiErr = getaddrinfo( host,
service,
&hints,
&aiHead ) ) != 0 )
{
fprintf( stderr,
"%s (line %d): ERROR - %s.\n",
pgmName,
__LINE__,
gai_strerror( aiErr ) );
return INVALID_DESC;
}
/*
** Go through the list and try to open a connection. Continue until
either
** a connection is established or the entire list is exhausted.
*/
for ( ai = aiHead, sckt = INVALID_DESC;
( ai != NULL ) && ( sckt == INVALID_DESC );
ai = ai->ai_next )
{
/*
** IPv6 kluge. Make sure the scope ID is set.
*/
if ( ai->ai_family == PF_INET6 )
{
pSadrIn6 = (sockaddr_in6_t*) ai->ai_addr;
if ( pSadrIn6->sin6_scope_id == 0 )
{
pSadrIn6->sin6_scope_id = scopeId;
} /* End IF the scope ID wasn't set. */
} /* End IPv6 kluge. */
/*
** Display the address info for the remote host.
*/
if ( verbose )
{
/*
** Temporary character string buffers for host & service.
*/
char hostBfr[ NI_MAXHOST ];
char servBfr[ NI_MAXSERV ];
/*
** Display the address information just fetched. Start with the
** common (protocol-independent) stuff first.
*/
fprintf( stderr,
"Address info:\n"
" ai_flags = 0x%02X\n"
" ai_family = %d (PF_INET = %d, PF_INET6 = %d)\n"
" ai_socktype = %d (SOCK_STREAM = %d, SOCK_DGRAM =
%d)\n"
" ai_protocol = %d (IPPROTO_TCP = %d, IPPROTO_UDP =
%d)\n"
" ai_addrlen = %d (sockaddr_in = %d, "
"sockaddr_in6 = %d)\n",
ai->ai_flags,
ai->ai_family,
PF_INET,
PF_INET6,
ai->ai_socktype,
SOCK_STREAM,
SOCK_DGRAM,
ai->ai_protocol,
IPPROTO_TCP,
IPPROTO_UDP,
ai->ai_addrlen,
sizeof( struct sockaddr_in ),
sizeof( struct sockaddr_in6 ) );
/*
** Display the protocol-specific formatted address.
*/
getnameinfo( ai->ai_addr,
ai->ai_addrlen,
hostBfr,
sizeof( hostBfr ),
servBfr,
sizeof( servBfr ),
NI_NUMERICHOST | NI_NUMERICSERV );
switch ( ai->ai_family )
{
case PF_INET: /* IPv4 address record. */
{
sockaddr_in_t *pSadrIn = (sockaddr_in_t*) ai->ai_addr;
fprintf( stderr,
" ai_addr = sin_family: %d (AF_INET = %d, "
"AF_INET6 = %d)\n"
" sin_addr: %s\n"
" sin_port: %s\n",
pSadrIn->sin_family,
AF_INET,
AF_INET6,
hostBfr,
servBfr );
break;
} /* End CASE of IPv4 record. */
case PF_INET6: /* IPv6 address record. */
{
pSadrIn6 = (sockaddr_in6_t*) ai->ai_addr;
fprintf( stderr,
" ai_addr = sin6_family: %d (AF_INET = %d, "
"AF_INET6 = %d)\n"
" sin6_addr: %s\n"
" sin6_port: %s\n"
" sin6_flowinfo: %d\n"
" sin6_scope_id: %d\n",
pSadrIn6->sin6_family,
AF_INET,
AF_INET6,
hostBfr,
servBfr,
pSadrIn6->sin6_flowinfo,
pSadrIn6->sin6_scope_id );
break;
} /* End CASE of IPv6 record. */
default: /* Can never get here, but just for completeness. */
{
fprintf( stderr,
"%s (line %d): ERROR - Unknown protocol family
(%d).\n",
pgmName,
__LINE__,
ai->ai_family );
break;
} /* End DEFAULT case (unknown protocol family). */
} /* End SWITCH on protocol family. */
} /* End IF verbose mode. */
/*
** Create a socket.
*/
if ( !SYSCALL( "socket",
__LINE__,
sckt = socket( ai->ai_family,
ai->ai_socktype,
ai->ai_protocol ) ) )
{
sckt = INVALID_DESC;
continue; /* Try the next address record in the list. */
}
/*
** Connect to the remote host.
*/
if ( !SYSCALL( "connect",
__LINE__,
connect( sckt,
ai->ai_addr,
ai->ai_addrlen ) ) )
{
(void) close( sckt ); /* Could use SYSCALL() again here, but why?
*/
sckt = INVALID_DESC;
continue; /* Try the next address record in the list. */
}
} /* End FOR each address record returned by getaddrinfo(3). */
/*
** Clean up & return.
*/
freeaddrinfo( aiHead );
return sckt;
} /* End openSckt() */
/
******************************************************************************
* Function: tod
*
* Description:
* Receive the time-of-day from the remote server and write it to stdout.
*
* Parameters:
* sckt - The socket descriptor for the connection.
*
* Return Value: None.
******************************************************************************/
static void tod( int sckt )
{
char bfr[ MAXBFRSIZE+1 ];
int inBytes;
/*
** The client never sends anything, so shut down the write side of the
** connection.
*/
if ( !SYSCALL( "shutdown",
__LINE__,
shutdown( sckt, SHUT_WR ) ) )
{
return;
}
/*
** Read the time-of-day from the remote host.
*/
do
{
if ( !SYSCALL( "read",
__LINE__,
inBytes = read( sckt,
bfr,
MAXBFRSIZE ) ) )
{
return;
}
bfr[ inBytes ] = '\0'; /* Null-terminate the received string. */
fputs( bfr, stdout ); /* Null string if EOF (inBytes == 0). */
} while ( inBytes > 0 );
fflush( stdout );
} /* End tod() */
1.4.3. 'Daytime' UDP Client Code
The UDP client code is found in file tod6uc.c (time-of-day IPv6 UDP client). It
is almost an exact duplicate of the TCP client (and in fact was derived from
it), but is included in this HowTo for completeness. Once built, the UDP client
may be started using the following command syntax (assuming tod6uc is the
executable file):
tod6uc [-v] [-s scope_id] [host [service]]
ARGUMENTS:
host
The hostname or IP address (dotted decimal or colon-hex) of the remote
host providing the service. Default is "localhost".
service
The UDP service (or well-known port number) to which datagrams are sent.
Default is "daytime".
OPTIONS:
-s
This option is only meaningful for IPv6 addresses, and is used to set the
scope identifier (i.e. the network interface on which to exchange
datagrams). Default is "eth0". If host is a scoped address, this option
is ignored.
-v
Turn on verbose mode.
The UDP client source code contained in tod6uc.c follows:
/
******************************************************************************
* File: tod6uc.c
* Description: Contains source code for an IPv6-capable 'daytime' UDP client.
* Author: John Wenker, Sr. Software Engineer
* Performance Technologies, San Diego, USA
******************************************************************************/
/*
** System header files.
*/
#include <errno.h> /* errno declaration and error codes.
*/
#include <net/if.h> /* if_nametoindex(3).
*/
#include <netdb.h> /* getaddrinfo(3) and associated definitions.
*/
#include <netinet/in.h> /* sockaddr_in and sockaddr_in6 definitions.
*/
#include <stdio.h> /* printf(3) et al.
*/
#include <stdlib.h> /* exit(2).
*/
#include <string.h> /* String manipulation and memory functions.
*/
#include <sys/socket.h> /* Socket functions (socket(2), connect(2), etc).
*/
#include <unistd.h> /* getopt(3), recvfrom(2), sendto(2), etc.
*/
/*
** Constants & macros.
*/
#define DFLT_HOST "localhost" /* Default server name. */
#define DFLT_SCOPE_ID "eth0" /* Default scope identifier. */
#define DFLT_SERVICE "daytime" /* Default service name. */
#define INVALID_DESC -1 /* Invalid file (socket) descriptor. */
#define MAXBFRSIZE 256 /* Max bfr sz to read remote TOD. */
#define VALIDOPTS "s:v" /* Valid command options. */
/*
** Type definitions (for convenience).
*/
typedef enum { false = 0, true } boolean;
typedef struct sockaddr_in sockaddr_in_t;
typedef struct sockaddr_in6 sockaddr_in6_t;
/*
** Prototypes for internal helper functions.
*/
static int openSckt( const char *host,
const char *service,
unsigned int scopeId );
static void tod( int sckt );
/*
** Global (within this file only) data objects.
*/
static const char *pgmName; /* Program name (w/o directory). */
static boolean verbose = false; /* Verbose mode. */
/*
** Usage macro.
*/
#define USAGE \
{ \
fprintf( stderr, \
"Usage: %s [-v] [-s scope_id] [host [service]]\n", \
pgmName ); \
exit( 127 ); \
} /* End USAGE macro. */
/*
** This "macro" (even though it's really a function) is loosely based on the
** CHK() macro by Dr. V. Vinge (see server code). The status parameter is
** a boolean expression indicating the return code from one of the usual
system
** calls that returns -1 on error. If a system call error occurred, an alert
** is written to stderr. It returns a boolean value indicating success/
failure
** of the system call.
**
** Example: if ( !SYSCALL( "write",
** count = write( fd, bfr, size ) ) )
** {
** // Error processing... but SYSCALL() will have already taken
** // care of dumping an error alert to stderr.
** }
*/
static __inline boolean SYSCALL( const char *syscallName,
int lineNbr,
int status )
{
if ( ( status == -1 ) && verbose )
{
fprintf( stderr,
"%s (line %d): System call failed ('%s') - %s.\n",
pgmName,
lineNbr,
syscallName,
strerror( errno ) );
}
return status != -1; /* True if the system call was successful. */
} /* End SYSCALL() */
/
******************************************************************************
* Function: main
*
* Description:
* Connect to a remote time-of-day service and write the remote host's TOD
to
* stdout.
*
* Parameters:
* The usual argc & argv parameters to a main() program.
*
* Return Value:
* This function always returns zero.
******************************************************************************/
int main( int argc,
char *argv[ ] )
{
const char *host = DFLT_HOST;
int opt;
int sckt;
unsigned int scopeId = if_nametoindex( DFLT_SCOPE_ID );
const char *service = DFLT_SERVICE;
/*
** Determine the program name (w/o directory prefix).
*/
pgmName = (const char*) strrchr( argv[ 0 ], '/' );
pgmName = pgmName == NULL ? argv[ 0 ] : pgmName+1;
/*
** Process command line options.
*/
opterr = 0; /* Turns off "invalid option" error messages. */
while ( ( opt = getopt( argc, argv, VALIDOPTS ) ) != -1 )
{
switch ( opt )
{
case 's': /* Scope identifier (IPv6 kluge). */
{
scopeId = if_nametoindex( optarg );
if ( scopeId == 0 )
{
fprintf( stderr,
"%s: Unknown network interface (%s).\n",
pgmName,
optarg );
USAGE;
}
break;
}
case 'v': /* Verbose mode. */
{
verbose = true;
break;
}
default:
{
USAGE;
}
} /* End SWITCH on command option. */
} /* End WHILE processing command options. */
/*
** Process command arguments. At the end of the above loop, optind is the
** index of the first NON-option argv element.
*/
switch ( argc - optind )
{
case 2: /* Both host & service are specified on the command line.
*/
{
service = argv[ optind + 1 ];
/***** Fall through *****/
}
case 1: /* Host is specified on the command line. */
{
host = argv[ optind ];
/***** Fall through *****/
}
case 0: /* Use default host & service. */
{
break;
}
default:
{
USAGE;
}
} /* End SWITCH on number of command arguments. */
/*
** Open a connection to the indicated host/service.
**
** Note that if all three of the following conditions are met, then the
** scope identifier remains unresolved at this point.
** 1) The default network interface is unknown for some reason.
** 2) The -s option was not used on the command line.
** 3) An IPv6 "scoped address" was not specified for the hostname on
the
** command line.
** If the above three conditions are met, then only an IPv4 socket can be
** opened (connect(2) fails without the scope ID properly set for IPv6
** sockets).
*/
if ( ( sckt = openSckt( host,
service,
scopeId ) ) == INVALID_DESC )
{
fprintf( stderr,
"%s: Sorry... a connectionless socket could "
"not be set up.\n",
pgmName );
exit( 1 );
}
/*
** Get the remote time-of-day.
*/
tod( sckt );
/*
** Close the connection and terminate.
*/
(void) SYSCALL( "close",
__LINE__,
close( sckt ) );
return 0;
} /* End main() */
/
******************************************************************************
* Function: openSckt
*
* Description:
* Sets up a UDP socket to a remote server. Getaddrinfo(3) is used to
* perform lookup functions and can return multiple address records (i.e. a
* list of 'struct addrinfo' records). This function traverses the list
and
* tries to establish a connection to the remote server. The function ends
* when either a connection has been established or all records in the list
* have been processed.
*
* Parameters:
* host - A pointer to a character string representing the hostname or
IP
* address (IPv4 or IPv6) of the remote server.
* service - A pointer to a character string representing the service name
or
* well-known port number.
* scopeId - For IPv6 sockets only. This is the index corresponding to the
* network interface on which to exchange datagrams. This
* parameter is ignored for IPv4 sockets or when an IPv6 "scoped
* address" is specified in 'host' (i.e. where the colon-hex
* network address is augmented with the scope ID).
*
* Return Value:
* Returns the socket descriptor for the connection, or INVALID_DESC if all
* address records have been processed and a socket could not be
initialized.
******************************************************************************/
static int openSckt( const char *host,
const char *service,
unsigned int scopeId )
{
struct addrinfo *ai;
int aiErr;
struct addrinfo *aiHead;
struct addrinfo hints;
sockaddr_in6_t *pSadrIn6;
int sckt;
/*
** Initialize the 'hints' structure for getaddrinfo(3).
**
** Notice that the 'ai_family' field is set to PF_UNSPEC, indicating to
** return both IPv4 and IPv6 address records for the host/service. Most
of
** the time, the user isn't going to care whether an IPv4 connection or an
** IPv6 connection is established; the user simply wants to exchange data
** with the remote host and doesn't care how it's done. Sometimes,
however,
** the user might want to explicitly specify the type of underlying
socket.
** It is left as an exercise for the motivated reader to add a command
line
** option allowing the user to specify the IP protocol, and then process
the
** list of addresses accordingly (it's not that difficult).
*/
memset( &hints, 0, sizeof( hints ) );
hints.ai_family = PF_UNSPEC; /* IPv4 or IPv6 records (don't care).
*/
hints.ai_socktype = SOCK_DGRAM; /* Connectionless communication.
*/
hints.ai_protocol = IPPROTO_UDP; /* UDP transport layer protocol only.
*/
/*
** Look up the host/service information.
*/
if ( ( aiErr = getaddrinfo( host,
service,
&hints,
&aiHead ) ) != 0 )
{
fprintf( stderr,
"%s (line %d): ERROR - %s.\n",
pgmName,
__LINE__,
gai_strerror( aiErr ) );
return INVALID_DESC;
}
/*
** Go through the list and try to open a connection. Continue until
either
** a connection is established or the entire list is exhausted.
*/
for ( ai = aiHead, sckt = INVALID_DESC;
( ai != NULL ) && ( sckt == INVALID_DESC );
ai = ai->ai_next )
{
/*
** IPv6 kluge. Make sure the scope ID is set.
*/
if ( ai->ai_family == PF_INET6 )
{
pSadrIn6 = (sockaddr_in6_t*) ai->ai_addr;
if ( pSadrIn6->sin6_scope_id == 0 )
{
pSadrIn6->sin6_scope_id = scopeId;
} /* End IF the scope ID wasn't set. */
} /* End IPv6 kluge. */
/*
** Display the address info for the remote host.
*/
if ( verbose )
{
/*
** Temporary character string buffers for host & service.
*/
char hostBfr[ NI_MAXHOST ];
char servBfr[ NI_MAXSERV ];
/*
** Display the address information just fetched. Start with the
** common (protocol-independent) stuff first.
*/
fprintf( stderr,
"Address info:\n"
" ai_flags = 0x%02X\n"
" ai_family = %d (PF_INET = %d, PF_INET6 = %d)\n"
" ai_socktype = %d (SOCK_STREAM = %d, SOCK_DGRAM =
%d)\n"
" ai_protocol = %d (IPPROTO_TCP = %d, IPPROTO_UDP =
%d)\n"
" ai_addrlen = %d (sockaddr_in = %d, "
"sockaddr_in6 = %d)\n",
ai->ai_flags,
ai->ai_family,
PF_INET,
PF_INET6,
ai->ai_socktype,
SOCK_STREAM,
SOCK_DGRAM,
ai->ai_protocol,
IPPROTO_TCP,
IPPROTO_UDP,
ai->ai_addrlen,
sizeof( struct sockaddr_in ),
sizeof( struct sockaddr_in6 ) );
/*
** Display the protocol-specific formatted address.
*/
getnameinfo( ai->ai_addr,
ai->ai_addrlen,
hostBfr,
sizeof( hostBfr ),
servBfr,
sizeof( servBfr ),
NI_NUMERICHOST | NI_NUMERICSERV );
switch ( ai->ai_family )
{
case PF_INET: /* IPv4 address record. */
{
sockaddr_in_t *pSadrIn = (sockaddr_in_t*) ai->ai_addr;
fprintf( stderr,
" ai_addr = sin_family: %d (AF_INET = %d, "
"AF_INET6 = %d)\n"
" sin_addr: %s\n"
" sin_port: %s\n",
pSadrIn->sin_family,
AF_INET,
AF_INET6,
hostBfr,
servBfr );
break;
} /* End CASE of IPv4 record. */
case PF_INET6: /* IPv6 address record. */
{
pSadrIn6 = (sockaddr_in6_t*) ai->ai_addr;
fprintf( stderr,
" ai_addr = sin6_family: %d (AF_INET = %d, "
"AF_INET6 = %d)\n"
" sin6_addr: %s\n"
" sin6_port: %s\n"
" sin6_flowinfo: %d\n"
" sin6_scope_id: %d\n",
pSadrIn6->sin6_family,
AF_INET,
AF_INET6,
hostBfr,
servBfr,
pSadrIn6->sin6_flowinfo,
pSadrIn6->sin6_scope_id );
break;
} /* End CASE of IPv6 record. */
default: /* Can never get here, but just for completeness. */
{
fprintf( stderr,
"%s (line %d): ERROR - Unknown protocol family
(%d).\n",
pgmName,
__LINE__,
ai->ai_family );
break;
} /* End DEFAULT case (unknown protocol family). */
} /* End SWITCH on protocol family. */
} /* End IF verbose mode. */
/*
** Create a socket.
*/
if ( !SYSCALL( "socket",
__LINE__,
sckt = socket( ai->ai_family,
ai->ai_socktype,
ai->ai_protocol ) ) )
{
sckt = INVALID_DESC;
continue; /* Try the next address record in the list. */
}
/*
** Set the target destination for the remote host on this socket. That
** is, this socket only communicates with the specified host.
*/
if ( !SYSCALL( "connect",
__LINE__,
connect( sckt,
ai->ai_addr,
ai->ai_addrlen ) ) )
{
(void) close( sckt ); /* Could use SYSCALL() again here, but why?
*/
sckt = INVALID_DESC;
continue; /* Try the next address record in the list. */
}
} /* End FOR each address record returned by getaddrinfo(3). */
/*
** Clean up & return.
*/
freeaddrinfo( aiHead );
return sckt;
} /* End openSckt() */
/
******************************************************************************
* Function: tod
*
* Description:
* Receive the time-of-day from the remote server and write it to stdout.
*
* Parameters:
* sckt - The socket descriptor for the connection.
*
* Return Value: None.
******************************************************************************/
static void tod( int sckt )
{
char bfr[ MAXBFRSIZE+1 ];
int inBytes;
/*
** Send a datagram to the server to wake it up. The content isn't
** important, but something must be sent to let it know we want the TOD.
*/
if ( !SYSCALL( "write",
__LINE__,
write( sckt, "Are you there?", 14 ) ) )
{
return;
}
/*
** Read the time-of-day from the remote host.
*/
if ( !SYSCALL( "read",
__LINE__,
inBytes = read( sckt,
bfr,
MAXBFRSIZE ) ) )
{
return;
}
bfr[ inBytes ] = '\0'; /* Null-terminate the received string. */
fputs( bfr, stdout ); /* Null string if EOF (inBytes == 0). */
fflush( stdout );
} /* End tod() */
2. Other programming languages
2.1. JAVA
Sun Java versions since 1.4 are IPv6 enabled, see e.g. Inet6Address_(1.5/5.0)
class. Hints are available in the Networking IPv6 User Guide for JDK/JRE 1.4
and 1.5_(5.0).
2.2. Perl
As of May 2007 it's not known that the Perl core itself already supports IPv6.
It can be added by using following modules:
* Socket6
Anyway, some other modules exist for/with IPv6 support (e.g. Net::IP), search
for â€IPv6†on http://search.cpan.org/.
Chapter 24. Interoperability
The TAHI_Project checks the interoperability of different operating systems
regarding the implementation of IPv6 features. Linux kernel already got the
IPv6_Ready_Logo_Phase_1.
Chapter 25. Further information and URLs
Table of Contents
1._Paper_printed_books,_articles,_online_reviews_(mixed)
1.1._Printed_Books_(English)
1.2._Articles,_eBooks,_Online_Reviews_(mixed)
1.3._Science_Publications_(abstracts,_bibliographies,_online_resources)
1.4._Others
2._Conferences,_Meetings,_Summits
2.1._2004
3._Online_information
3.1._Join_the_IPv6_backbone
3.2._Latest_news_and_URLs_to_other_documents
3.3._Protocol_references
3.4._More_information
3.5._By_countries
3.6._By_operating_systems
3.7._IPv6_Security
3.8._Application_lists
4._IPv6_Infrastructure
4.1._Statistics
4.2._Internet_Exchanges
4.3._Tunnel_broker
4.4._Native_IPv6_Services
5._Maillists
6._Online_tools
6.1._Testing_tools
6.2._Information_retrievement
6.3._IPv6_Looking_Glasses
6.4._Helper_applications
7._Trainings,_Seminars
8._'The_Online_Discovery'_...
1. Paper printed books, articles, online reviews (mixed)
1.1. Printed Books (English)
1.1.1. Cisco
* Cisco Self-Study: Implementing IPv6 Networks (IPV6) by Regis Desmeules. Cisco
Press; ISBN 1587050862; 500 pages; 1st edition (April 11, 2003). Note: This
item will be published on April 11, 2003.
* Configuring IPv6 with Cisco IOS by Sam Brown, Sam Browne, Neal Chen, Robbie
Harrell, Edgar, Jr. Parenti (Editor), Eric Knipp (Editor), Paul Fong
(Editor)362 pages; Syngress Media Inc; ISBN 1928994849; (July 12, 2002).
1.1.2. General
* IPv6_in_Practice:_A_Unixer's_Guide_to_the_Next_Generation_Internet von
Benedikt Stockebrand, November 2006; ISBN 3-540-24524-3
* IPv6_Essentials by Silvia Hagen, 2nd Edition, May 2006; ISBN 0-5961-0058-
2 ToC,_Index,_Sample_Chapter_etc.; O'Reilly_Pressrelease
* IPv6: The New Internet Protocol. By Christian Huitema; Published by Prentice-
Hall; ISBN 0138505055. Description: This book, written by Christian Huitema -
a member of the InternetArchitecture Board, gives an excellent description of
IPv6, how it differs from IPv4, and the hows and whys of it's development.
Source: http://www.cs.uu.nl/wais/html/na-dir/internet/tcp-ip/resource-
list.html
* IPv6_Networks by Niles, Kitty; (ISBN 0070248079); 550 pages; Date Published
05/01/1998.
* Implementing IPV6. Supporting the Next Generation Internet Protocols by P. E.
Miller, Mark A. Miller; Publisher: John Wiley & Sons; ISBN 0764545892;
2nd edition (March 15, 2000); 402 pages.
* Big Book of Ipv6 Addressing Rfcs by Peter H. Salus (Compiler), Morgan
Kaufmann Publishers, April 2000, 450 pages ISBN 0126167702.
* Understanding_IPV6 by Davies, Joseph; ISBN 0735612455; Date Published 05/01/
2001; Number of Pages: 350.
* Migrating to IPv6 - IPv6 in Practice by Marc Blanchet Publisher: John Wiley
& Sons; ISBN 0471498920; 1st edition (November 2002); 368 pages.
* Ipv6 Network Programming by Jun-ichiro Hagino; ISBN 1555583180
* Wireless_boosting_IPv6 by Carolyn Duffy Marsan, 10/23/2000.
* O'reilly_Network_search_for_keyword_IPv6 results in 29 hits (28. January
2002)
1.2. Articles, eBooks, Online Reviews (mixed)
* Getting_Connected_with_6to4 by Huber Feyrer, 06/01/2001
* Transient Addressing for Related Processes: Improved Firewalling by Using
IPv6 and Multiple Addresses per Host; written by Peter M. Gleiz, Steven M.
Bellovin (PC-PDF-Version; Palm-PDF-Version; PDB-Version)
* Internetworking_IPv6_with_Cisco_Routers by Silvano Gai, McGrawHill Italia,
1997. The 13 chapters and appendix A-D are downloadable as PDF-documents.
* Migration_and_Co-existence_of_IPv4_and_IPv6_in_Residential_Networks by Pekka
Savola, CSC/FUNET, 2002
1.3. Science Publications (abstracts, bibliographies, online resources)
See also: liinwww.ira.uka.de/ipv6 or Google_/_Scholar_/_IPv6
* GEANT_IPv6_Workplan
* IPv6_Trials_on_UK_Academic_Networks:_Bermuda_Project_Aug.2002: Participants -
Getting connected - Project deliverables - Network topology - Address
assignments - Wireless IPv6 access - IPv6 migration - Project presentations -
Internet 2 - Other IPv6 projects - IPv6 fora and standards Bermuda 2...
* http://www.ipv6.ac.uk/
* IPv6_at_the_University_of_Southampton
* Microsoft Research IPv6 Implementation (MSRIPv6): MSRIPv6_Configuring_6to4_-
Connectivity_with_MSR_IPv6_-_Our_6Bone_Node...
1.4. Others
See following URL for more: SWITCH_IPv6_Pilot_/_References
2. Conferences, Meetings, Summits
Something missing? Suggestions are welcome!
2.1. 2004
* 1st Global IPv6 Summit in Sao Paul, Brazil
3. Online information
3.1. Join the IPv6 backbone
More to be filled later...suggestions are welcome!
3.1.1. Global registries
See regional registries.
3.1.2. Major regional registries
* America: ARIN, ARIN_/_registration_page, ARIN_/_IPv6_guidelines
* EMEA: Ripe_NCC, Ripe_NCC_/_registration_page, Ripe_NCC_/_IPv6_registration
* Asia/Pacific: APNIC, APNIC_/_IPv6_ressource_guide
* Latin America and Caribbea: LACNIC, IPv6_Registration_Services, IPv6
Allocation_Policy
* Africa: AfriNIC
Also a list of major (prefix length 32) allocations per local registry is
available here: Ripe_NCC_/_IPv6_allocations.
3.1.3. Tunnel brokers
Note: A list of available Tunnel broker can be found in the section Tunnel
broker below.
* Former IPng. Tunnelbroker and IPv6 resources, now migrated to the SixXs
System.
* Eckes' IPv6-with-Linux Page.
* tunnelc - a perl based tunnel client script: freshmeat.net: Project_details
for_tunnel_client SourceForge: Project_Info_-_tunnelc (also here)
* Linux Advanced Routing & Traffic Control HOWTO, Chapter_6:_IPv6_tunneling
with_Cisco_and/or_6bone.
3.1.4. 6to4
* NSayer's_6to4_information
* RFC_3068_/_An_Anycast_Prefix_for_6to4_Relay_Routers
3.1.5. ISATAP
* ISATAP_(Intra-Site_Automatic_Tunnel_Access_Protocol)_Information by JOIN
3.2. Latest news and URLs to other documents
* Lot_of_URLs_to_others_documents by Anil Edathara
* go6_-_The_IPv6_Portal: an IPv6 online portal with a wiki-based IPv6 knowledge
center, an IPv6 discussion forum, an up-to-date collection of IPv6 Events and
News, free IPv6 access and services, IPv6 software applications, and much
more
3.3. Protocol references
3.3.1. IPv6-related Request For Comments (RFCs)
Publishing the list of IPv6-related RFCs is beyond the scope of this document,
but given URLs will lead you to such lists:
* List sorted by IPng_Standardization_Status or IPng_Current_Specifications by
Robert Hinden
* IPv6_Related_Specifications on IPv6.org
3.3.2. Current drafts of working groups
Current (also) IPv6-related drafts can be found here:
* IP_Version_6_(ipv6)
* Next_Generation_Transition_(ngtrans)
* Dynamic_Host_Configuration_(dhc)
* Domain_Name_System_Extension_(dnsext)
* IPv6_Operations_(v6ops)
* Mobile_IP_(mobileip)
* Get_any_information_about_IPv6,_from_overviews,_through_RFCs_&_drafts,_to
implementations (including availability of stacks on various platforms &
source code for IPv6 stacks)
3.3.3. Others
* SWITCH_IPv6_Pilot_/_References, big list of IPv6 references maintained by
Simon Leinen
3.4. More information
DeepSpace6_/_more_interesting_links
3.4.1. Linux related
* DeepSpace6_/_(Not_only)_Linux_IPv6_Portal - Italy (Mirror)
* IPv6-HowTo_for_Linux_by_Peter_Bieringer - Germany, and his Bieringer_/_IPv6_-
software_archive
* Linux+IPv6_status_by_Peter_Bieringer - Germany (going obsolete)
* DeepSpace6_/_IPv6_Status_Page - Italy (Mirror) (will superseed upper one)
* USAGI_project - Japan, and their USAGI_project_-_software_archive
* Linux_Optimized_Link_State_Routing_Protocol_(OLSR)_IPv6_HOWTO
* LinShim6
3.4.2. Linux related per distribution
PLD
PLD_Linux_Distribution (â€market leader†in containing IPv6 enabled
packages)
Red Hat
Red_Hat_Enterprise_Linux, Pekka_Savola's_IPv6_packages_(Historic)
Fedora
Fedora_(Project)_Linux
Debian
Debian_Linux, IPv6_with_Debian_Linux
SuSE
SuSE_Linux
Mandriva
Mandriva_(Historic)
For more see the IPv6+Linux_Status_Distributions page.
3.4.3. General
* IPv6.org
* 6bone
* WIDE_project - Japan
* SWITCH_IPv6_Pilot - Switzerland
* IPv6_Corner_of_Hubert_Feyrer - Germany
* IPv6_Forum - a world-wide consortium of leading Internet vendors, Research
& Education Networks...
* Playground.sun.com_/_IPv6_Info_Page - maintained by Robert Hinden, Nokia. Get
any information about IPv6, from overviews, through RFCs & drafts, to
implementations (including availability of stacks on various platforms &
source code for IPv6 stacks).
* 6INIT - IPv6 Internet Initiative - an EU Fifth Framework Project under the
IST Programme.
* IPv6_Task_Force_(European_Union)
* 6init - IPv6 INternet IniTiative
* IPv6:_The_New_Version_of_the_Internet_Protocol, by Steve Deering.
* IPv6:_The_Next_Generation_Internet_Protocol, by Gary C. Kessler.
* IPv6:_Next_Generation_Internet_Protocol - 3Com
* internet_||_site and internet2_Working_Group
* NetworkWorldFusion: Search / Doc Finder: searched_for_IPv6 (102 documents
found 22.12.2002)
* The_Register (Search for IPv6 will result in 30 documents, 22.12.2002)
* ZDNet_Search_for_IPv6
* TechTarget_Search_for_IPv6
* IPv6_&_TCP_Resources_List
Something missing? Suggestions are welcome!
3.4.4. Market Research
* statista_-_The_Statistics_Portal
* Market_Research
3.4.5. Patents
* Delphion Research: Patent_Search_Page. Basic (free) registration needed.
Examples found 21.12.2002 searching for IPv6: Communicating_method_between
IPv4_terminal_and_IPv6_terminal_and_IPv4-IPv6_converting_apparatus Translator
for_IP_networks,_network_system_using_the_translator,_and_IP_network_coupling
method_therefor
3.5. By countries
3.5.1. Europe
* www.ist-ipv6.org: IST IPv6 Cluster, European IPv6 Research and Development
Projects
* Euro6IX: European IPv6 Internet Exchanges Backbone
3.5.2. Austria
* IPv6@IKNnet_and_MIPv6_Research_Group: TU Vienna, Austria (IPv6: project,
publications, diploma / doctor thesis, Conference Proceedings etc.)
3.5.3. Australia
* Carl's_Australian_IPv6_Pages (old content)
3.5.4. Belgium
Suggestions are welcome!
3.5.5. Brasil
* IPv6_do_Brasil
3.5.6. China
Suggestions are welcome!
3.5.7. Czech
Suggestions are welcome!
3.5.8. Germany
* Xing_/_IPv6
3.5.9. France
* Renater: Renater IPv6 Project Page
* IPv6_-_RSVP_-_ATM_at_INRIA
* NetBSD_IPv6_Documentation
3.5.10. Italy
* Project6: IPv6 networking with Linux
3.5.11. Japan
* Yamaha_IPv6 (sorry, all in japanese native ...)
3.5.12. Korea
* ETRI: Electronics and Telecommunications Research Institut
* IPv6_Forum_Korea: Korean IPv6 Deployment Project
3.5.13. Mexico
* IPv6_Mexico (spain & english version): IPv6 Project Hompeage of The
National Autonomous University of Mexico (UNAM)
3.5.14. Netherland
* SURFnet: SURFnet IPv6 Backbone
* STACK, STACK_(IPv6): Students' computer association of the Eindhoven
University of Technology, Netherland
* IPng.nl: collaboration between WiseGuys and Intouch
3.5.15. Portugal
Suggestions are welcome!
3.5.16. Russia
* IPv6_Forum_for_Russia: Yaroslavl State University Internet Center
3.5.17. Switzerland
Suggestions are welcome!
3.5.18. United Kingdom
* British_Telecom_IPv6_Home: BT's ISP IPv6 Trial, UK's first IPv6 Internet
Exchange etc.
3.6. By operating systems
3.6.1. *BSD
* KAME_project (*BSD)
* NetBSD's_IPv6_Networking_FAQ
* FreeBSD_Ports:_Ipv6
3.6.2. Cisco IOS
* Cisco_IOS_IPv6_Entry_Page
* IPv6_for_Cisco_IOS_Software, File 2 of 3: Aug 2002 -- Table of Contents: IPv6
for Cisco IOS Software; Configuring Documentation Specifics; Enabling IPv6
Routing and Configuring; IPv6 Addressing; Enabling IPv6 Processing Globally.
* Cisco Internet Networking Handbook, Chapter_IPv6
3.6.3. HPUX
* comp.sys.hp.hpux_FAQ
3.6.4. IBM
* Now that IBM's announced the availability of z/OS V1.4, what's_new_in_this
release? This question was posed on 15 August 2002
3.6.5. Microsoft
* Microsoft_Windows_2000_IPv6
* MSRIPv6 - Microsoft Research Network - IPv6 Homepage
* Internet_Connection_Firewall_Does_Not_Block_Internet_Protocol_Version_6
Traffic (6.11.2001)
* Internet_Protocol_Numbers (8.10.2002)
* IPv6_Technology_Preview_Refresh (16.10.2002)
* HOW_TO:_Install_and_Configure_IP_Version_6_in_Windows_.NET_Enterprise_Server
(26.10.2002)
* Windows_.NET_Server_6to4_Router_Service_Quits_When_You_Advertise_a_2002
Address_on_the_Public_Interface (28.10.2002)
* msdn_-_Microsoft_Windows_CE_.NET_-_IPv6_commands
3.6.6. Solaris
* Sun_Microsystems_Solaris
* Solaris_2_Frequently_Asked_Questions_(FAQ)_1.73
3.6.7. Sumitoma
* Sumitomo_Electric_has_implemented_IPv6_on_Suminet_3700_family_routers
3.6.8. ZebOS
* IpInfusion's ZebOS_Server_Routing_Software
3.7. IPv6 Security
* NIST_IPsec_Project ( National Institute of Standards and Technology, NIST)
* Information_Security
* NewOrder.box.sk_(search_for_IPv6) (Articles, exploits, files database etc.)
3.8. Application lists
* DeepSpace6_/_IPv6_Status_Page (Mirror)
* IPv6.org_/_IPv6_enabled_applications
* Freshmeat_/_IPv6_search, currently (14 Dec 2002) 62 projects
* IPv6_Forum_/_Web_Links
3.8.1. Analyzer tools
* Wireshark (former known as Ethereal) is a free network protocol analyzer for
Unix and Windows
* Radcom_RC100-WL - Download Radcom RC100-WL protocol analyzer version 3.20
3.8.2. IPv6 Products
* 6wind - solutions for IPv4/IPv6 Router, QoS, Multicast, Mobility, Security/
VPN/Firewall.
* Fefe's_patches_for_IPv6_with_djbdnsAug 2002 -- What is djbdns and why does it
need IPv6? djbdns is a full blown DNS server which outperforms BIND in nearly
all respects.
* ZebOS_Server_Routing_Suite
* Inframail_(Advantage_Server_Edition)
* HTTrack_Website_Copier
* CommView
* Posadis
3.8.3. SNMP
* comp.protocpols.snmp_SNMP_FAQ_Part_1_of_2
4. IPv6 Infrastructure
4.1. Statistics
* IPv6_routing_table_history created by Gert Döring, Space.Net
* Official_6bone_Webserver_list_Statisic
4.2. Internet Exchanges
Another list of IPv6 Internet Exchanges can be found here: IPv6_status_of_IXPs
in_Europe
4.2.1. Estonia
* TIX (tallinn interneti exchange with ipv6 support)
4.2.2. Europe
* Euro6IX, European IPv6 Internet Exchange Backbone
4.2.3. France
* French_National_Internet_Exchange_IPv6 (since 1.11.2002 active). FNIX6
provides a free and reliable high speed FastEthernet interconnection between
ISP located in TeleCity Paris.
4.2.4. Germany
* INXS: (Cable & Wireless) Munich and Hamburg
4.2.5. Japan
* NSPIXP-6: IPv6-based Internet Exchange in Tokyo
* JPIX, Tokyo
4.2.6. Korea
* 6NGIX
4.2.7. Netherlands
* AMS-IX: Amsterdam Internet Exchange
4.2.8. UK
* UK6X: London
* XchangePoint: London
4.2.9. USA
* 6TAP: Chicago. Supports peerings around the globe.
* PAIX: Palo Alto
4.3. Tunnel broker
See also: http://www.deepspace6.net/docs/tunnelbrokers.html
4.3.1. Belgium
Something missing? Suggestions are welcome!
4.3.2. Canada
* Freenet6 - /48 Delegation, Canada Getting_IPv6_Using_Freenet6_on_Debian
Freenet6_creater
4.3.3. China
Something missing? Suggestions are welcome!
4.3.4. Estonia
* Estpak
4.3.5. Germany
* 6bone_Knoten_Leipzig Info_bez._Hackangriff_(2001)
4.3.6. Italy
* Comv6
* Bersafe (Italian language)
4.3.7. Japan
Something missing? Suggestions are welcome!
4.3.8. Malaysia
Something missing? Suggestions are welcome!
4.3.9. Netherlands
* IPng_Netherland - Intouch, SurfNet, AMS-IX, UUNet, Cistron, RIPE NCC and
AT&T are connected at the AMS-IX. It is possible (there are
requirements...) to get an static tunnel.
* SURFnet_Customers
4.3.10. Norway
* UNINETT - Pilot IPv6 Service (for Customers): tunnelbroker & address
allocation Uninett-Autoupdate-HOWTO
4.3.11. Spain
* Consulintel
4.3.12. Switzerland
Something missing? Suggestions are welcome!
4.3.13. UK
* NTT, United Kingdom - IPv6 Trial. IPv4 Tunnel and native IPv6 leased Line
connections. POPs are located in London, UK Dusseldorf, Germany New Jersey,
USA (East Coast) Cupertino, USA (West Coast) Tokyo, Japan
4.3.14. USA
* ESnet, USA - Energy Sciences Network: Tunnel Registry & Address
Delegation for directly connected ESnet sites and ESnet collaborators.
* Hurricane_Electric, US backbone; Hurrican_Electric_Tunnelbroker (also
available under http://tunnelbroker.com/) Press Release: Hurricane_Electric
Upgrades_IPv6_Tunnel_Broker Tunnel_Broker_Endpoint_Autoupdate, Perl Script
4.3.15. Singapore
Something missing? Suggestions are welcome!
4.3.16. More Tunnel brokers...
* Public_6to4_relay_routers (MS IIE boycott!)
4.4. Native IPv6 Services
Note: These services are mostly only available with a valid IPv6 connection!
4.4.1. Net News (NNTP)
Something missing? Suggestions are welcome!
4.4.2. Game Server
* Quake2 over IPv6
4.4.3. IRC Server
Something missing? Suggestions are welcome!
4.4.4. Radio Stations, Music Streams
Something missing? Suggestions are welcome!
4.4.5. Webserver
* Peter_Bieringer's_Home_of_Linux_IPv6_HOWTO
Something missing? Suggestions are welcome!
5. Maillists
Lists of maillists are available at:
* DeepSpace6_/_Mailling_Lists
Major Mailinglists are listed in following table:
_________________________________________________________________________________
| Focus | Request e-mail | What to | Maillist e-mail |Language| Access |
|____________|______address____|subscribe|_____address_____|________|_through_WWW_|
|Linux kernel| majordomo (at) | netdev | netdev (at) |English |Info, Archive|
| networking | vger.kernel.org | | vger.kernel.org | | |
| including | | | | | |
|____IPv6____|_________________|_________|_________________|________|_____________|
| Mobile IP | Web-based, see | mipl |mipl (at) mobile-|English |Info, Archive|
| (v6) for | URL | | ipv6.org | | |
|____Linux___|_________________|_________|_________________|________|_____________|
| Linux IPv6 |usagi-users-ctl | Â |usagi-users (at) |English | Info_/ |
|users using | (at) linux- | | linux-ipv6.org | | Search, |
| USAGI | ipv6.org | | | | Archive |
|_extension__|_________________|_________|_________________|________|_____________|
| IPv6 on | Â | Â |debian-ipv6 (at) |English | Info/ |
|Debian Linux| | |lists.debian.org | |Subscription/|
|____________|_________________|_________|_________________|________|___Archive___|
| 6bone | majordomo (at) | 6bone | 6bone (at) |English |Info, Archive|
|____________|______isi.edu____|_________|_______isi.edu___|________|_____________|
| IPv6 users | majordomo (at) | users | users (at) |English |Info, Archive|
|_in_general_|_____ipv6.org____|_________|______ipv6.org___|________|_____________|
|Bugtracking |bugtraq-subscribe| Â | bugtraq (at) |English |Info, Archive|
|of Internet | (at) | |securityfocus.com| | |
|applications|securityfocus.com| | (2) | | |
|____(1)_____|_________________|_________|_________________|________|_____________|
(1) very recommended if you provide server applications.
(2) list is moderated.
Something missing? Suggestions are welcome!
Following other maillinglists & newsgroups are available via web:
* student-ipv6_(India) Description: This is the group for the Student Awareness
group of IPv6 in India
* sun-ipv6-users Description: Please report problems/suggestions regarding SUN
Microsystems IPng implementation
* IPv6-BITS Description: This List will co-ordinate the working of Project
Vertebrae.
* linux-bangalore-ipv6 Description: The IPv6 deployment list of the Bangalore
Linux User Group
* packet-switching Description: This mailing list provides a forum for
discussion of packet switching theory, technology, implementation and
application in any relevant aspect including without limitation LAPB, X.25,
SDLC, P802.1d, LLC, IP, IPv6, IPX, DECNET, APPLETALK, FR, PPP, IP Telephony,
LAN PBX systems, management protocols like SNMP, e-mail, network transparent
window systems, protocol implementation, protocol verification, conformance
testing and tools used in maintaining or developing packet switching systems.
* de.comm.protocols.tcp-ip Description: Umstellung auf IPv6 Source: Chartas_der
Newsgruppen_in_de.*
* Google Group: comp.protocols.tcp-ip
* Google Group: linux.debian.maint.ipv6
* Google Group: microsoft.public.platformsdk.networking.ipv6
* Google Group: fa.openbsd.ipv6
6. Online tools
6.1. Testing tools
* ping, traceroute, tracepath, 6bone registry, DNS: JOIN_/_Testtools (German
language only, but should be no problem for non German speakers)
* traceroute6, whois: IPng.nl
* AAAA Lookup Checker http://www.cnri.dit.ie/cgi-bin/check_aaaa.pl
6.2. Information retrievement
* List_of_worldwide_all_IPv6-aggregated_IP-Blocks
6.3. IPv6 Looking Glasses
* DRENv6_Looking_Glass
6.4. Helper applications
* IPv6_Prefix_Calculator by TDOI
* DNS_record_checker
7. Trainings, Seminars
* CIW_Internetworking_Professional_Training_CBT_CD
* Training_Pages, U.K. - Search for IPv6 (13 Courses, 2006-08-21)
* Erion_IPv6_Training, UK
Something missing? Suggestions are welcome!
8. 'The Online Discovery' ...
IPv6: Addressing The Needs Of the Future by Yankee Group (Author) List Price:
$595.00 Edition: e-book (Acrobat Reader) Pages: 3 (three) Publisher:
MarketResearch.com; ISBN B00006334Y; (November 1, 2001)
;-) The number of copies would be interesting...
Chapter 26. Revision history / Credits / The End
Table of Contents
1._Revision_history
1.1._Releases_0.x
2._Credits
2.1._Major_credits
2.2._Other_credits
3._The_End
1. Revision history
Versions x.y are published on the Internet.
Versions x.y.z are work-in-progress and published as LyX and SGML file on CVS.
Because Deep Space 6 mirrors these SGML files and generate independend from
TLDP public versions, this versions will show up there and also on its mirrors.
1.1. Releases 0.x
0.67wip
2015-08-18/PB: fix some broken URLs, 20151016/bie: remove broken URL to
Spanish transation, 20161215/bie: update some URLs, 20170114/: update
some URLs
0.66
2010-04-20/PB: extend QoS section with examples, 20130513/PB: add IPv6
NAT hints, 20130521/PB: review dhcpd, 20131019/bie: general review,
20140502/bie: add hints for nftables, 20140513/bie: extend section
regarding address resolution and add source/destination address selection
information, 20140515/bie: add hints for activation of privacy extension
0.65
2009-12-13/PB: minor fixes
0.64
2009-06-11/PB: extend DHCP server examples (ISC DHCP, Dibbler)
0.63
2009-02-14/PB: Fix FSF address, major update on 4in6 tunnels, add new
section for address resolving, add some URLs, remove broken URLs
0.62
2008-11-09/PB: Adjust URL to Turkish howto, add some HIP related URLs,
remove broken URLs
0.61.1
2007-11-11/PB: fix broken description of shortcut BIND
0.61
2007-10-06/PB: fix broken URLs to TLDP-CVS, minor URL update.
0.60.2
2007-10-03/PB: fix description of sysctl/autoconf (credits to Francois-
Xavier Le Bail)
0.60.1
2007-06-16/PB: speling fixes (credits to Larry W. Burton)
0.60
2007-05-29/PB: import major contribution to Programming using C-API
written by John Wenker, minor fixes
0.52
2007-05-23/PB: update firewalling chapter, improve document for proper
SGML validation, minor bugfixes
0.51
2006-11-08/PB: remove broken URLs, add a new book (credits to Bryan
Vukich)
0.50.2
2006-10-25/PB: fix typo in dhcp6 section (credits to Michele Ferritto)
0.50.1
2006-09-23/PB: add some URLs
0.50
2006-08-24/PB: check RFC URLs, fix URL to Chinese translation, finalize
for publishing
0.49.5
2006-08-23/PB: fix/remove broken URLs
0.49.4
2006-08-21/PB: some review, update and enhancement of the content,
replace old 6bone example addresses with the current defined ones.
0.49.3
2006-08-20/PB: fix bug in maillist entries, 'mobility' is now a separate
chapter
0.49.2
2006-08-20/PB: update and cleanup of maillist entries
0.49.1
2006-06-13/PB: major update of mobility section (contributed by Benjamin
Thery)
0.49
2005-10-03/PB: add configuration hints for DHCPv6, major broken URL
cleanup (credits to Necdet Yucel)
0.48.1
2005-01-15/PB: minor fixes
0.48
2005-01-11/PB: grammar check and minor review of IPv6 IPsec section
0.47.1
2005-01-01/PB: add information and examples about IPv6 IPsec, add some
URLs
0.47
2004-08-30/PB: add some notes about proftpd, vsftpd and other daemons,
add some URLs, minor fixes, update status of Spanish translation
0.46.4
2004-07-19/PB: minor fixes
0.46.3
2004-06-23/PB: add note about started Greek translation, replace
Taiwanese with Chinese for related translation
0.46.2
2004-05-22/PB: minor fixes
0.46.1
2004-04-18/PB: minor fixes
0.46
2004-03-04/PB: announce Italian translation, add information about
DHCPv6, minor updates
0.45.1
2004-01-12/PB: add note about the official example address space
0.45
2004-01-11/PB: minor fixes, add/fix some URLs, some extensions
0.44.2
2003-10-30/PB: fix some copy&paste text bugs
0.44.1
2003-10-19/PB: add note about start of Italian translation
0.44
2003-08-15/PB: fix URLs, add hint on tcp_wrappers (about broken notation
in some versions) and Apache2
0.43.4
2003-07-26/PB: fix URL, add archive URL for maillist users at ipv6.org,
add some ds6 URLs
0.43.3
2003-06-19/PB: fix typos
0.43.2
2003-06-11/PB: fix URL
0.43.1
2003-06-07/PB: fix some URLs, fix credits, add some notes at IPsec
0.43
2003-06-05/PB: add some notes about configuration in SuSE Linux, add URL
of French translation
0.42
2003-05-09/PB: minor fixes, announce French translation
0.41.4
2003-05-02/PB: Remove a broken URL, update some others.
0.41.3
2003-04-23/PB: Minor fixes, remove a broken URL, fix URL to Taiwanese
translation
0.41.2
2003-04-13/PB: Fix some typos, add a note about a French translation is
in progress
0.41.1
2003-03-31/PB: Remove a broken URL, fix another
0.41
2003-03-22/PB: Add URL of German translation
0.40.2
2003-02-27/PB: Fix a misaddressed URL
0.40.1
2003-02-12/PB: Add Debian-Linux-Configuration, add a minor note on
translations
0.40
2003-02-10/PB: Announcing available German version
0.39.2
2003-02-10/GK: Minor syntax and spelling fixes
0.39.1
2003-01-09/PB: fix an URL (draft adopted to an RFC)
0.39
2003-01-13/PB: fix a bug (forgotten 'link†on â€ip link set†(credits to
Yaniv Kaul)
0.38.1
2003-01-09/PB: a minor fix
0.38
2003-01-06/PB: minor fixes
0.37.1
2003-01-05/PB: minor updates
0.37
2002-12-31/GK: 270 new links added (searched in 1232 SearchEngines) in
existing and 53 new (sub)sections
0.36.1
2002-12-20/PB: Minor fixes
0.36
2002-12-16/PB: Check of and fix broken links (credits to Georg Käfer),
some spelling fixes
0.35
2002-12-11/PB: Some fixes and extensions
0.34.1
2002-11-25/PB: Some fixes (e.g. broken linuxdoc URLs)
0.34
2002-11-19/PB: Add information about German translation (work in
progress), some fixes, create a small shortcut explanation list, extend
â€used terms†and add two German books
0.33
2002-11-18/PB: Fix broken RFC-URLs, add parameter ttl on 6to4 tunnel
setup example
0.32
2002-11-03/PB: Add information about Taiwanese translation
0.31.1
2002-10-06/PB: Add another maillist
0.31
2002-09-29/PB: Extend information in proc-filesystem entries
0.30
2002-09-27/PB: Add some maillists
0.29
2002-09-18/PB: Update statement about nmap (triggered by Fyodor)
0.28.1
2002-09-16/PB: Add note about ping6 to multicast addresses, add some
labels
0.28
2002-08-17/PB: Fix broken LDP/CVS links, add info about Polish
translation, add URL of the IPv6 Address Oracle
0.27
2002-08-10/PB: Some minor updates
0.26.2
2002-07-15/PB: Add information neighbor discovery, split of firewalling
(got some updates) and security into extra chapters
0.26.1
2002-07-13/PB: Update nmap/IPv6 information
0.26
2002-07-13/PB: Fill /proc-filesystem chapter, update DNS information
about depricated A6/DNAME, change P-t-P tunnel setup to use of â€ip†only
0.25.2
2002-07-11/PB: Minor spelling fixes
0.25.1
2002-06-23/PB: Minor spelling and other fixes
0.25
2002-05-16/PB: Cosmetic fix for 2^128, thanks to José AbÃlio Oliveira
Matos for help with LyX
0.24
2002-05-02/PB: Add entries in URL list, minor spelling fixes
0.23
2002-03-27/PB: Add entries in URL list and at maillists, add a label and
minor information about IPv6 on RHL
0.22
2002-03-04/PB: Add info about 6to4 support in kernel series 2.2.x and add
an entry in URL list and at maillists
0.21
2002-02-26/PB: Migrate next grammar checks submitted by John Ronan
0.20.4
2002-02-21/PB: Migrate more grammar checks submitted by John Ronan, add
some additional hints at DNS section
0.20.3
2002-02-12/PB: Migrate a minor grammar check patch submitted by John
Ronan
0.20.2
2002-02-05/PB: Add mipl to maillist table
0.20.1
2002-01-31/PB: Add a hint how to generate 6to4 addresses
0.20
2002-01-30/PB: Add a hint about default route problem, some minor updates
0.19.2
2002-01-29/PB: Add many new URLs
0.19.1
2002-01-27/PB: Add some forgotten URLs
0.19
2002-01-25/PB: Add two German books, fix quote entinities in exported
SGML code
0.18.2
2002-01-23/PB: Add a FAQ on the program chapter
0.18.1
2002-01-23/PB: Move â€the end†to the end, add USAGI to maillists
0.18
2002-01-22/PB: Fix bugs in explanation of multicast address types
0.17.2
2002-01-22/PB: Cosmetic fix double existing text in history (at 0.16),
move all credits to the end of the document
0.17.1
2002-01-20/PB: Add a reference, fix URL text in online-test-tools
0.17
2002-01-19/PB: Add some forgotten information and URLs about global IPv6
addresses
0.16
2002-01-19/PB: Minor fixes, remove â€bold†and â€emphasize†formats on code
lines, fix â€too long unwrapped code lines†using selfmade utility, extend
list of URLs.
0.15
2002-01-15/PB: Fix bug in addresstype/anycast, move content related
credits to end of document
0.14
2002-01-14/PB: Minor review at all, new chapter â€debuggingâ€, review
â€addressesâ€, spell checking, grammar checking (from beginning to 3.4.1)
by Martin Krafft, add tcpdump examples, copy firewalling/netfilter6 from
IPv6+Linux-HowTo, minor enhancements
0.13
2002-01-05/PB: Add example BIND9/host, move revision history to end of
document, minor extensions
0.12
2002-01-03/PB: Merge review of David Ranch
0.11
2002-01-02/PB: Spell checking and merge review of Pekka Savola
0.10
2002-01-02/PB: First public release of chapter 1
2. Credits
The quickest way to be added to this nice list is to send bug fixes,
corrections, and/or updates to me ;-).
If you want to do a major review, you can use the native LyX file (see original
source) and send diffs against it, because diffs against SGML don't help too
much.
2.1. Major credits
* David Ranch <dranch at trinnet dot net>: For encouraging me to write this
HOWTO, his editorial comments on the first few revisions, and his
contributions to various IPv6 testing results on my IPv6 web site. Also for
his major reviews and suggestions.
* Pekka Savola <pekkas at netcore dot fi>: For major reviews, input and
suggestions.
* Martin F. Krafft <madduck at madduck dot net>: For grammar checks and general
reviewing of the document.
* John Ronan <j0n at tssg dot wit dot ie>: For grammar checks.
* Georg Käfer <gkaefer at gmx dot at>: For detection of no proper PDF creation
(fixed now by LDP maintainer Greg Ferguson), input for German books, big list
of URLs, checking all URLs, many more suggestions, corrections and
contributions, and the German translation
* Michel Boucey <mboucey at free dot fr>: Finding typos and some broken URLs,
contribute some suggestions and URLs, and the French translation
* Michele Ferritto <m dot ferritto at virgilio dot it>: Finding bugs and the
Italian translation
* Daniel Roesen <dr at cluenet dot de>: For grammar checks
* Benjamin Thery <benjamin dot thery at bull dot net>: For contribution of
updated mobility section
* John Wenker <jjw at pt dot com>: major contribution to Programming using C-
API
* Srivats P. <Srivats dot P at conexant dot com>: major contribution for 4in6
tunnels
2.2. Other credits
2.2.1. Document technique related
Writing a LDP HOWTO as a newbie (in LyX and exporting this to DocBook to
conform to SGML) isn't as easy as some people say. There are some strange
pitfalls... Nevertheless, thanks to:
* Authors of the LDP_Author_Guide
* B. Guillon: For his DocBook_with_LyX_HOWTO
2.2.2. Content related credits
Credits for fixes and hints are listed here, will grow sure in the future
* S .P. Meenakshi <meena at cs dot iitm dot ernet dot in>: For a hint using a
â€send mail†shell program on tcp_wrapper/hosts.deny
* Frank Dinies <FrankDinies at web dot de>: For a bugfix on IPv6 address
explanation
* John Freed <jfreed at linux-mag dot com>: For finding a bug in IPv6 multicast
address explanation
* Craig Rodrigues <crodrigu at bbn dot com>: For suggestion about RHL IPv6
setup
* Fyodor <fyodor at insecure dot org>: Note me about outdated nmap information
* Mauro Tortonesi <mauro at deepspace6 dot net>: For some suggestions
* Tom Goodale <goodale at aei-potsdam dot mpg dot de>: For some suggestions
* Martin Luemkemann <mluemkem at techfak dot uni-bielefeld dot de>: For a
suggestion
* Jean-Marc V. Liotier <jim at jipo dot com>: Finding a bug
* Yaniv Kaul <ykaul at checkpoint dot com>: Finding a bug
* Arnout Engelen <arnouten at bzzt dot net>: For sending note about a draft was
adopted to RFC now
* Stephane Bortzmeyer <bortzmeyer at nic dot fr>: Contributing persistent
configuration on Debian
* lithis von saturnsys <lithis at saturnsys dot com>: Reporting a misaddressed
URL
* Guy Hulbert <gwhulbert at rogers dot com>: Send a note that RFC1924 is
probably an April fool's joke
* Tero Pelander <tpeland at tkukoulu dot fi>: Reporting a broken URL
* Walter Jontofsohn <wjontof at gmx dot de>: Hints for SuSE Linux 8.0/8.1
* Benjamin Hofstetter <benjamin dot hofstetter at netlabs dot org>: Reporting a
mispointing URL
* J.P. Larocque <piranha at ely dot ath dot cx>: Reporting archive URL for
maillist users at ipv6 dot org
* Jorrit Kronjee <jorrit at wafel dot org>: Reporting broken URLs
* Colm MacCarthaigh <colm dot maccarthaigh at heanet dot ie>: Hint for sendfile
issue on Apache2
* Tiago Camilo <tandre at ipg dot pt>: Contribute some URLs about Mobile IPv6
* Harald Geiger: Reporting a bug in how described the bit counting of the
universal/global bit
* Bjoern Jacke <bjoern at j3e dot de>: Triggered me to fix some outdated
information on xinetd
* Christoph Egger <cegger at chrrr dot com>: Sending note about â€ip†has
problems with IPv4-compatible addresses on SuSE Linux 9.0 and trigger to add
a hint on 6to4-radvd example
* David Lee Haw Ling <hawling at singnet dot com dot sg>: Sending information
about a tunnel broker
* Michael H. Warfield <mhw at iss dot net>: Sending note about suffix for 6to4
routers
* Tomasz Mrugalski <thomson at klub dot com dot pl>: Sending updates for DHCPv6
section
* Jan Minar <jjminar at fastmail dot fm>: Reporting minor bugs
* Kalin KOZHUHAROV <kalin at tar dot bz>: Fixing a not so well explanation
* Roel van Dijk <rdvdijk at planet dot nl>: Reporting broken URLs
* Catalin Muresan <catalin dot muresan at astral dot ro>: Reporting minor bugs
* Dennis van Dok <dvandok at quicknet dot nl>: Reporting minor bugs
* Necdet Yucel <nyucel at comu dot edu dot tr>: Reporting broken URLs
* Bryan Vukich: Reporting a broken URL
* Daniele Masini: reporting a broken iptables example
* Yao Zhao: reporting a bug in IPv6 route remove description
* Aaron Kunde: reporting a broken URL and a content related bug
* Larry W. Burton: speling fixes
* Justin Pryzby: reporting broken shortcut description of BIND
3. The End
Thanks for reading. Hope it helps!
If you have any questions, subscribe to proper maillist and describe your
problem providing as much as information as possible.