RFC 1412 (rfc1412) - Page 2 of 4

Telnet Authentication: SPX

RFC 1412                     SPX for Telnet                 January 1993


      (A document which describes the mutual response syntax is forth
      coming.)  If the AUTH_HOW_ONE_WAY bit is set in the second octet
      of the authentication-type-pair, the sender includes zero bytes of
      mutual response.

   IAC SB AUTHENTICATION REPLY  REJECT
    IAC SE

      This command indicates that the authentication was not successful,
      and if there is any more data in the sub-option, it is an ASCII
      text message of the reason for the rejection.

3.  Implementation Rules

   Every command after the first AUTHENTICATION IS must carry the same
   set of modifiers (e.g., CLIENT|MUTUAL) for subsequent AUTHENTICATION
   IS and AUTHENTICATION REPLY commands.

   If the second octet of the authentication-type-pair has the AUTH_WHO
   bit set to AUTH_WHO_CLIENT, then the client sends the initial AUTH
   command, and the server responds with either ACCEPT or REJECT.

   If the second octet of the authentication-type-pair has the AUTH_WHO
   bit set to AUTH_WHO_SERVER, then the server sends the initial AUTH
   command, and the client responds with either ACCEPT or REJECT.

4.  Examples

   User "joe" may wish to log in as user "pete" on machine "foo".  If
   "pete" has set things up on "foo" to allow "joe" access to his
   account, then the client would send IAC SB AUTHENTICATION NAME "pete"
   IAC SE IAC SB AUTHENTICATION IS SPX AUTH  IAC SE.  The server would then authenticate the user as "joe"
   from the token information, and the server would send back either
   ACCEPT or REJECT.  If mutual authentication is being used, the server
   would include in the ACCEPT message, a mutual response.  The
   authorization check to see if "pete" is allowing "joe" to use his
   account is made after the authentication exchange is complete.
   Therefore, it is possible for the client to receive an ACCEPT
   response (based on the authentication token), but for joe to be
   denied access to log in to pete's account.










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