telnetd(1M)                  UNIX System V(TCP/IP)                  telnetd(1M)


NAME
      telnetd - DARPA TELNET protocol server

SYNOPSIS
      in.telnetd

DESCRIPTION
      telnetd is a server which supports the DARPA standard TELNET virtual
      terminal protocol.  telnetd is invoked by the internet server [see
      inetd(1M)], normally for requests to connect to the TELNET port as
      indicated by the /etc/services file [see services(4)].

      telnetd operates by allocating a pseudo-terminal device for a client,
      then creating a login process which has the slave side of the pseudo-
      terminal as its standard input, output, and error.  The login process is
      an instance of the in.login program, which is based on login(1).  It is
      invoked with the -h option to indicate that it is originated by telnetd.
      telnetd manipulates the master side of the pseudo-terminal, implementing
      the TELNET protocol and passing characters between the remote client and
      the login process.

      When a TELNET session is started up, telnetd sends TELNET options to the
      client side indicating a willingness to do remote echo of characters, to
      suppress go ahead, and to receive terminal type information from the
      remote client.  If the remote client is willing, the remote terminal type
      is propagated in the environment of the created login process.  The
      pseudo-terminal allocated to the client is configured to operate in
      cooked mode, and with XTABS, ICRNL, and ONLCR enabled [see
      termio(4)].

      telnetd is willing to do:  echo, binary, suppress go ahead, and timing
      mark.
      telnetd is willing to have the remote client do:  binary, terminal type,
      and suppress go ahead.

SEE ALSO
      telnet(1)

      Postel, Jon, and Joyce Reynolds, ``Telnet Protocol Specification,'' RFC
      854, Network Information Center, SRI International, Menlo Park, Calif.,
      May 1983.

NOTES
      Some TELNET commands are only partially implemented.

      The TELNET protocol allows for the exchange of the number of lines and
      columns on the user's terminal, but telnetd doesn't make use of them.

      Binary mode has no common interpretation except between similar operating
      systems




10/89                                                                    Page 1

telnetd(1M)                  UNIX System V(TCP/IP)                  telnetd(1M)


      The terminal type name received from the remote client is converted to
      lower case.

      The packet interface to the pseudo-terminal should be used for more
      intelligent flushing of input and output queues.

      telnetd never sends TELNET go ahead commands.

      telnetd can only support 64 pseudo-terminals.













































Page 2                                                                    10/89