telnetd(1M)                     TCP/IP R4.11                     telnetd(1M)


NAME
       telnetd - DARPA TELNET protocol server

SYNOPSIS
       telnetd [ -h ] [ -b bannerfile ]

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.  telnetd
       manipulates the master side of the pseudo-terminal, implementing the
       TELNET protocol and passing characters between the remote client and
       the login process.  On a system with DG/UX information security, the
       login process requires that the user be specifically authorized for
       telnet service.

       Options are:

       -h     Do not display the default telnetd-provided banner containing
              the host release and name.

       -b     Display the contents of this user-provided banner file after
              any other banner display.

       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 and
       window size 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 and the X window size is placed in its
       stty settings.

       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.

       (Pertains to a system with DG/UX information security)
                 WARNING: Currently, between a remote host and a host with
                 security and mandatory access control (MAC), there is no
                 protocol for passing the MAC label of the remote session.
                 Thus, there is no way to enforce the same MAC level on the
                 two systems.  If a remote user is allowed to telnet at a
                 classified clearance, then there is a high risk that
                 confidential information can be compromised.

SEE ALSO
       telnet(1C), inetd.conf(4M).

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

NOTES
       telnetd has been reimplemented in STREAMS for improved performance.
       This means that TELNET must be configured into the kernel through the
       system file resulting in a /dev/telnet file.  Also, the
       /etc/inetd.conf entry for TELNET must have "tli" in the type column,
       not "stream" [see inetd.conf(4M)].

       Some TELNET commands are only partially implemented.

       The TELNET protocol uses the Negotiate About Window Size protocol
       sequence to allow for the exchange of the number of lines and columns
       on the user's terminal.

       Binary mode has no common interpretation except between similar
       operating systems.

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

       telnetd never sends TELNET go ahead commands.


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