ASCII and Hex Representation of NetBIOS Names

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This article was previously published under Q194203

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SUMMARY

NetBIOS names are 16 bytes long, but they are mapped to a 32-byte wide string of alphabet (A,B...O,P) using a reversible, half-ASCII, biased encoding.

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MORE INFORMATION

The algorithm used to encode NetBIOS names is as follows:

Each half-octet of the NetBIOS name is encoded into 1 byte of the 32-byte field. The first half-octet is encoded into the first byte, the second half- octet into the second byte, and so on. Each 4-bit, half-octet of the NetBIOS name is treated as an 8-bit, right-adjusted, zero-filled binary number. This number is added to the value of the ASCII character 'A' (hexadecimal 41). The resulting 8-bit number is stored in the appropriate byte.

This encoding results in a NetBIOS name being represented as a sequence of 32 ASCII, upper-case characters from the set {A,B,C...N,O,P}. The NetBIOS scope identifier is a valid domain name (without a leading dot).

An ASCII dot (2E hexadecimal) and the scope identifier are appended to the encoded form of the NetBIOS name, the result forming a valid domain name.

For example, the NetBIOS name "THE NETBIOS NAME" in the NetBIOS scope "SCOPE.ID.COM" would be represented at level one by the ASCII character string:

   FEEIEFCAEOEFFEECEJEPFDCAEOEBENEF.SCOPE.ID.COM

The following is a list of characters and their corresponding encoded ASCII and hex values:

   Character   ASCII Code    Hex Code
   ----------------------------------

   A            EB            45 42
   B            EC            45 43
   C            ED            45 44
   D            EE            45 45
   E            EF            45 46
   F            EG            45 47
   G            EH            45 48
   H            EI            45 49
   I            EJ            45 4A
   J            EK            45 4B
   K            EL            45 4C
   L            EM            45 4D
   M            EN            45 4E
   N            EO            45 4F
   O            EP            45 50
   P            FA            46 41
   Q            FB            46 42
   R            FC            46 43
   S            FD            46 44
   T            FE            46 45
   U            FF            46 46
   V            FG            46 47
   W            FH            46 48
   X            FI            46 49
   Y            FJ            46 4A
   Z            FK            46 4B

   0            DA            44 41
   1            DB            44 42
   2            DC            44 43
   3            DD            44 44
   4            DE            44 45
   5            DF            44 46
   6            DG            44 47
   7            DH            44 48
   8            DI            44 49
   9            DJ            44 4A

   <space>      CA            43 41
   !            CB            43 42
   "            CC            43 43
   #            CD            43 44
   $            CE            43 45
   %            CF            43 46
   &            CG            43 47
   '            CH            43 48
   (            CI            43 49
   )            CJ            43 4A
   *            CK            43 4B
   +            CL            43 4C
   ,(comma)     CM            43 4D
   -(hyphen)    CN            43 4E
   .(period)    CO            43 4F
   =            DN            44 4E
   :(colon)     DK            44 4B
   ;(semicolon) DL            44 4C
   @            EA            45 41
   ^            FO            46 4F
   _(underscore)FP            46 50
   {            HL            48 4C
   }            HN            48 4E
   ~            HO            48 4F

NOTE: The above mapping list can be useful while reading network traces because information is sent on the wire in the above encoded format.

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