RFC 859 (rfc859) - Page 2 of 3

Telnet Status Option

RFC 859                                                         May 1983


   could lead to the nonterminating request loop problem discussed in
   the General Consideration section of the TELNET Specification.  This
   option fits into the normal structure of TELNET options by deferring
   the actual transfer of status information to the SB command.

5. Description of the Option

   WILL and DO are used only to obtain and grant permission for future
   discussion. The actual exchange of status information occurs within
   option subcommands (IAC SB STATUS...).

   Once the two hosts have exchanged a WILL and a DO, the sender of the
   WILL STATUS is free to transmit status information, spontaneously or
   in response to a request from the sender of the DO. At worst, this
   may lead to transmitting the information twice. Only the sender of
   the DO may send requests (IAC SB STATUS SEND IAC SE) and only the
   sender of the WILL may transmit actual status information (within an
   IAC SB STATUS IS ... IAC SE command).

   IS has the subcommands WILL, DO and SB. They are used EXACTLY as used
   during the actual negotiation of TELNET options, except that SB is
   terminated with SE, rather than IAC SE. Transmission of SE, as a
   regular data byte, is accomplished by doubling the byte (SE SE).
   Options that are not explicitly described are assumed to be in their
   default states. A single IAC SB STATUS IS ... IAC SE describes the
   condition of ALL options.
























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