181 lines
5.0 KiB
Groff
181 lines
5.0 KiB
Groff
.\" Copyright (c) 1983 The Regents of the University of California.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)telnetd.8 6.8 (Berkeley) 4/20/91
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.\"
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.TH TELNETD 8 "April 20, 1991"
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.UC 5
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.SH NAME
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telnetd \- DARPA TELNET protocol server
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.SH SYNOPSIS
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.B /etc/telnetd
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[\fB\-debug\fP [\fIport\fP]]
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[\fB\-l]
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[\fB\-D options\fP]
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[\fB\-D report\fP]
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[\fB\-D exercise\fP]
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[\fB\-D netdata\fP]
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[\fB\-D ptydata\fP]
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.SH DESCRIPTION
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.I Telnetd
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is a server which supports the DARPA standard
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.B TELNET
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virtual terminal protocol.
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.I Telnetd
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is invoked by the internet server (see
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.IR inetd (8)),
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normally for requests to connect to the
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.B TELNET
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port as indicated by the
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.I /etc/services
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file (see
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.IR services (5)).
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If the \fB\-debug\fP may be used, to start up \fBtelnetd\fP
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manually, instead of through
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.IR inetd (8).
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If started up this way, \fIport\fP may be specified to
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run \fItelnetd\fP on an alternate TCP port number.
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.PP
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The \fB\-D\fP option may be used for debugging purposes.
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This allows \fItelnet\fR to print out debugging information
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to the connection, allowing the user to see what telnetd
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is doing.
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There are several modifiers:
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\fBoptions\fR prints information about the negotiation
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of \fBTELNET\fR options,
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\fBreport\fR prints the \fBoptions\fR information, plus
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some additional information about what processing is going on,
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\fBnetdata\fP displays the data stream received by \fItelnetd\fP,
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\fBptydata\fP displays data written to the pty, and
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\fBexercise\fR has not been implemented yet.
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.PP
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.I Telnetd
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operates by allocating a pseudo-terminal device (see
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.IR pty (4))
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for a client, then creating a login process which has
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the slave side of the pseudo-terminal as
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.BR stdin ,
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.BR stdout ,
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and
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.BR stderr .
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.I Telnetd
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manipulates the master side of the pseudo-terminal,
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implementing the
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.B TELNET
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protocol and passing characters
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between the remote client and the login process.
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.PP
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When a
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.B TELNET
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session is started up,
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.I telnetd
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sends
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.B TELNET
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options to the client side indicating
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a willingness to do
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.I remote echo
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of characters, to
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.I suppress go
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.IR ahead ,
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to do
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.I remote flow
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.IR control ,
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and to receive
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.I terminal type
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.IR information ,
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.I terminal speed
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.IR information ,
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and
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.I window size information
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from the remote client.
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If the remote client is willing, the remote terminal type is
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propagated in the environment of the created login process.
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The pseudo-terminal allocated to the client is configured
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to operate in \*(lqcooked\*(rq mode, and with XTABS and CRMOD
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enabled (see
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.IR tty (4)).
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.PP
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.I Telnetd
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is willing to
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.IR do :
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.IR echo ,
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.IR binary ,
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.I suppress go
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.IR ahead ,
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and
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.I timing
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.IR mark .
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.I Telnetd
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is willing to have the remote client
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.IR do :
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.IR linemode ,
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.IR binary ,
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.I terminal
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.IR type ,
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.I terminal
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.IR speed ,
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.I window
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.IR size ,
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.I toggle flow
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.IR control ,
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.IR environment ,
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.I X display
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.IR location ,
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and
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.I suppress go
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.IR ahead .
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.SH "SEE ALSO"
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telnet(1)
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.SH BUGS
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Some
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.B TELNET
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commands are only partially implemented.
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.PP
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Because of bugs in the original 4.2 BSD
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.IR telnet (1),
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.I telnetd
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performs some dubious protocol exchanges to try to discover if the remote
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client is, in fact, a 4.2 BSD
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.IR telnet (1).
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.PP
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.I Binary mode
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has no common interpretation except between similar operating systems
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(Unix in this case).
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.PP
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The terminal type name received from the remote client is converted to
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lower case.
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.PP
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.I Telnetd
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never sends
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.B TELNET
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.I go ahead
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commands.
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