4.4BSD/usr/src/libexec/telnetd/telnetd.8

Compare this file to the similar file:
Show the results in this format:
.\" Copyright (c) 1983, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"	@(#)telnetd.8	8.1 (Berkeley) 6/4/93
.\"
.TH TELNETD 8 "June 4, 1993"
.UC 5
.SH NAME
telnetd \- DARPA TELNET protocol server
.SH SYNOPSIS
.B /etc/telnetd
[\fB\-debug\fP [\fIport\fP]]
[\fB\-l]
[\fB\-D options\fP]
[\fB\-D report\fP]
[\fB\-D exercise\fP]
[\fB\-D netdata\fP]
[\fB\-D ptydata\fP]
.SH DESCRIPTION
.I Telnetd
is a server which supports the DARPA standard
.B TELNET
virtual terminal protocol.
.I Telnetd
is invoked by the internet server (see
.IR inetd (8)),
normally for requests to connect to the
.B TELNET
port as indicated by the
.I /etc/services
file (see
.IR services (5)).
If the \fB\-debug\fP may be used, to start up \fBtelnetd\fP
manually, instead of through
.IR inetd (8).
If started up this way, \fIport\fP may be specified to
run \fItelnetd\fP on an alternate TCP port number.
.PP
The \fB\-D\fP option may be used for debugging purposes.
This allows \fItelnet\fR to print out debugging information
to the connection, allowing the user to see what telnetd
is doing.
There are several modifiers:
\fBoptions\fR prints information about the negotiation
of \fBTELNET\fR options,
\fBreport\fR prints the \fBoptions\fR information, plus
some additional information about what processing is going on,
\fBnetdata\fP displays the data stream received by \fItelnetd\fP,
\fBptydata\fP displays data written to the pty, and
\fBexercise\fR has not been implemented yet.
.PP
.I Telnetd
operates by allocating a pseudo-terminal device (see
.IR pty (4))
for a client, then creating a login process which has
the slave side of the pseudo-terminal as 
.BR stdin ,
.BR stdout ,
and
.BR stderr .
.I Telnetd
manipulates the master side of the pseudo-terminal,
implementing the
.B TELNET
protocol and passing characters
between the remote client and the login process.
.PP
When a
.B TELNET
session is started up, 
.I telnetd
sends
.B TELNET
options to the client side indicating
a willingness to do
.I remote echo
of characters, to
.I suppress go
.IR ahead ,
to do
.I remote flow
.IR control ,
and to receive
.I terminal type
.IR information ,
.I terminal speed
.IR information ,
and
.I 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.
The pseudo-terminal allocated to the client is configured
to operate in \*(lqcooked\*(rq mode, and with XTABS and CRMOD
enabled (see
.IR tty (4)).
.PP
.I Telnetd
is willing to
.IR do :
.IR echo ,
.IR binary ,
.I suppress go
.IR ahead ,
and
.I timing
.IR mark .
.I Telnetd
is willing to have the remote client
.IR do :
.IR linemode ,
.IR binary ,
.I terminal
.IR type ,
.I terminal
.IR speed ,
.I window
.IR size ,
.I toggle flow
.IR control ,
.IR environment ,
.I X display
.IR location ,
and
.I suppress go
.IR ahead .
.SH "SEE ALSO"
telnet(1)
.SH BUGS
Some
.B TELNET
commands are only partially implemented.
.PP
Because of bugs in the original 4.2 BSD
.IR telnet (1),
.I telnetd
performs some dubious protocol exchanges to try to discover if the remote
client is, in fact, a 4.2 BSD
.IR telnet (1).
.PP
.I Binary mode
has no common interpretation except between similar operating systems
(Unix in this case).
.PP
The terminal type name received from the remote client is converted to
lower case.
.PP
.I Telnetd
never sends
.B TELNET
.I go ahead
commands.