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.\" Copyright (c) 1983, 1990 The Regents of the University of California.
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.\" All rights reserved.
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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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.\" 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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.\" 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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.\" from: @(#)telnet.1 6.16 (Berkeley) 7/27/91
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.\" $Id: telnet.1,v 1.15 2000/07/30 23:57:08 dholland Exp $
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.Os "Linux NetKit (0.17)"
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.Nd user interface to the
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.Op Fl e Ar escapechar
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is used for interactive communication with another host using the
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protocol. It begins in command mode, where it prints a telnet prompt
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argument, it performs an
67
command implicitly; see the description below.
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.Bl -tag -width indent
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Force IPv4 address resolution.
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Force IPv6 address resolution.
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Request 8-bit operation. This causes an attempt to negotiate the
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option for both input and output. By default telnet is not 8-bit
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Disables the escape character functionality; that is, sets the escape
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character to ``no character''.
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Specifies an 8-bit data path on output. This causes the
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option to be negotiated on just output.
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Attempt automatic login. Currently, this sends the user name via the
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option if supported by the remote system. The username is retrieved
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Sets the initial value of the
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In this mode, the default escape character is a tilde. Also, the
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interpretation of the escape character is changed: an escape character
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followed by a dot causes
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to disconnect from the remote host. A ^Z instead of a dot suspends
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and a ^] (the default
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escape character) generates a normal telnet prompt. These codes are
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accepted only at the beginning of a line.
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Sets the IP type-of-service (TOS) option for the telnet
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connection to the value
118
.It Fl e Ar escapechar
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Sets the escape character to
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If no character is supplied, no escape character will be used.
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Entering the escape character while connected causes telnet to drop to
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as the user to log in as on the remote system. This is accomplished by
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sending the specified name as the
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environment variable, so it requires that the remote system support the
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option. This option implies the
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option, and may also be used with the
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.It Fl n Ar tracefile
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for recording trace information.
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Specifies a host to contact over the network.
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Specifies a port number or service name to contact. If not specified,
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Once a connection has been opened,
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will attempt to enable the
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will revert to one of two input modes:
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either \*(Lqcharacter at a time\*(Rq
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or \*(Lqold line by line\*(Rq
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depending on what the remote system supports.
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is enabled, character processing is done on the
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local system, under the control of the remote system. When input
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editing or character echoing is to be disabled, the remote system
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will relay that information. The remote system will also relay
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changes to any special characters that happen on the remote
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system, so that they can take effect on the local system.
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In \*(Lqcharacter at a time\*(Rq mode, most
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text typed is immediately sent to the remote host for processing.
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In \*(Lqold line by line\*(Rq mode, all text is echoed locally,
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and (normally) only completed lines are sent to the remote host.
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The \*(Lqlocal echo character\*(Rq (initially \*(Lq^E\*(Rq) may be used
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to turn off and on the local echo
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(this would mostly be used to enter passwords
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without the password being echoed).
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option is enabled, or if the
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(the default for \*(Lqold line by line\*(Lq; see below),
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characters are trapped locally, and sent as
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protocol sequences to the remote side.
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has ever been enabled, then the user's
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There are options (see
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which cause this action to flush subsequent output to the terminal
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(until the remote host acknowledges the
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sequence) and flush previous terminal input
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commands are available. Unique prefixes are understood as abbreviations.
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.Bl -tag -width "mode type"
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.It Ic auth Ar argument ...
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.Dv TELNET AUTHENTICATE
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was compiled without authentication, the
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command will not be supported.
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Valid arguments are as follows:
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.Bl -tag -width "disable type"
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.It Ic disable Ar type
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Disable the specified type of authentication. To
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obtain a list of available types, use the
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.It Ic enable Ar type
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Enable the specified type of authentication. To
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obtain a list of available types, use the
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List the current status of the various types of
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Note that the current version of
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does not support authentication.
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Close the connection to the remote host, if any, and return to command
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.It Ic display Ar argument ...
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Display all, or some, of the
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.It Ic encrypt Ar argument ...
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The encrypt command controls the
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was compiled without encryption, the
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command will not be supported.
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Valid arguments are as follows:
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.It Ic disable Ar type Ic [input|output]
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Disable the specified type of encryption. If you do not specify input
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or output, encryption of both is disabled. To obtain a list of
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available types, use ``encrypt disable \&?''.
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.It Ic enable Ar type Ic [input|output]
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Enable the specified type of encryption. If you do not specify input
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or output, encryption of both is enabled. To obtain a list of
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available types, use ``encrypt enable \&?''.
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This is the same as ``encrypt start input''.
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This is the same as ``encrypt stop input''.
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This is the same as ``encrypt start output''.
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This is the same as ``encrypt stop output''.
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.It Ic start Ic [input|output]
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Attempt to begin encrypting. If you do not specify input or output,
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encryption of both input and output is started.
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Display the current status of the encryption module.
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.It Ic stop Ic [input|output]
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Stop encrypting. If you do not specify input or output, encryption of
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Sets the default type of encryption to be used with later ``encrypt start''
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or ``encrypt stop'' commands.
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Note that the current version of
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does not support encryption.
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.It Ic environ Ar arguments...
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command is used to propagate environment variables across the
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All variables exported from the shell are defined, but only the
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variables are marked to be sent by default. The
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variable is marked to be sent if the
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command-line options were used.
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Valid arguments for the
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.It Ic define Ar variable value
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Any variables defined by this command are automatically marked for
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propagation (``exported'').
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may be enclosed in single or double quotes so
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that tabs and spaces may be included.
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.It Ic undefine Ar variable
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Remove any existing definition of
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.It Ic export Ar variable
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Mark the specified variable for propagation to the remote host.
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.It Ic unexport Ar variable
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Do not mark the specified variable for propagation to the remote
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host. The remote host may still ask explicitly for variables that are
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List the current set of environment variables.
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will be propagated to the remote host. The remote host may still ask
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explicitly for the rest.
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Prints out help information for the
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protocol option to the remote host.
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This command is similar to a
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command. If the remote host does not support the
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option, nothing happens. But if it does, this command should cause it
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to close the connection. If the remote side also supports the concept
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of suspending a user's session for later reattachment, the logout
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command indicates that the session should be terminated immediately.
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is one of several options, depending on the state of the session.
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asks the remote host to go into the requested mode. If the remote host
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says it can, that mode takes effect.
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option, or, if the remote side does not understand the
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option, then enter \*(Lqcharacter at a time\*(Lq mode.
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option, or, if the remote side does not understand the
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option, then attempt to enter \*(Lqold-line-by-line\*(Lq mode.
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.It Ic isig Pq Ic \-isig
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Attempt to enable (disable) the
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This requires that the
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.It Ic edit Pq Ic \-edit
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Attempt to enable (disable) the
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This requires that the
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.It Ic softtabs Pq Ic \-softtabs
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Attempt to enable (disable) the
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This requires that the
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.It Ic litecho Pq Ic \-litecho
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Attempt to enable (disable) the
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This requires that the
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Prints out help information for the
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Open a connection to the named host. If no port number is specified,
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will attempt to contact a
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daemon at the standard port (23).
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The host specification may be a host name or IP address.
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option may be used to specify a user name to be passed to the remote
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When connecting to ports other than the
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protocol negotiations. This makes it possible to connect to services
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that do not support the
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protocol without making a mess. Protocol negotiation can be forced by
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placing a dash before the port number.
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After establishing a connection, any commands associated with the
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file are executed, in that order.
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The format of the telnetrc files is as follows: Lines beginning with a
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#, and blank lines, are ignored. The rest of the file should consist
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of hostnames and sequences of
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commands to use with that host. Commands should be one per line,
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indented by whitespace; lines beginning without whitespace are
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interpreted as hostnames. Lines beginning with the special hostname
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will apply to all hosts. Upon connecting to a particular host, the
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commands associated with that host are executed.
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Close any open session and exit
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An end of file condition on input, when in command mode, will trigger
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this operation as well.
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.It Ic send Ar arguments
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Send one or more special
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protocol character sequences to the remote host. The following are
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the codes which may be specified (more than one may be used in one
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.Bl -tag -width escape
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(Abort Processes) sequence.
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(Abort Output) sequence, which should cause the remote system to flush
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(Are You There?) sequence, to which the remote system may or may not
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(Break) sequence, which may have significance to the remote
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sequence, which should cause the remote system to erase the last character
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sequence, which should cause the remote system to erase the line currently
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sequence, which likely has no significance to the remote system.
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If the remote side supports the
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will send the subnegotiation to request that the server send
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its current option status.
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(Interrupt Process) sequence, which should cause the remote
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system to abort the currently running process.
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This sequence causes the remote system to discard all previously typed
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(but not yet read) input.
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This sequence is sent as
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data (and may not work if the remote system is a
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it doesn't work, a lower case \*(Lqr\*(Rq may be echoed on the terminal).
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can be either a decimal number between 0 and 255,
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or a symbolic name for a specific
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to print out help information, including
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a list of known symbolic names.
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Prints out help information for the
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.It Ic set Ar argument value
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.It Ic unset Ar argument value
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command will set any one of a number of
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variables to a specific value or to
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turns off the function associated with
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the variable. This is equivalent to using the
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command will disable or set to
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any of the specified variables.
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The values of variables may be interrogated with the
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The variables which may be set or unset, but not toggled, are
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listed here. In addition, any of the variables for the
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command may be explicitly set or unset.
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.Bl -tag -width escape
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is in localchars mode, or
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is enabled, and the status character is typed, a
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sequence is sent to the remote host. The initial value for the "Are
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You There" character is the terminal's status character.
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This is the value (initially \*(Lq^E\*(Rq) which, when in
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\*(Lqline by line\*(Rq mode, toggles between doing local echoing
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of entered characters (for normal processing), and suppressing
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echoing of entered characters (for entering, say, a password).
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or \*(Lqold line by line\*(Rq mode, entering this character
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as the first character on a line will cause this character to be
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sent to the remote system.
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The initial value of the eof character is taken to be the terminal's
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is operating in \*(Lqcharacter at a time\*(Rq mode, then when this
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character is typed, a
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is sent to the remote system.
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The initial value for the erase character is taken to be
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escape character (initially \*(Lq^[\*(Rq) which causes entry
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command mode (when connected to a remote system).
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character is typed, a
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is sent to the remote host.
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The initial value for the flush character is taken to be
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characters that, when typed, cause partial lines to be
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forwarded to the remote system. The initial value for
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the forwarding characters are taken from the terminal's
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eol and eol2 characters.
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character is typed, a
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is sent to the remote host.
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The initial value for the interrupt character is taken to be
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is operating in \*(Lqcharacter at a time\*(Rq mode, then when this
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character is typed, a
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is sent to the remote system.
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The initial value for the kill character is taken to be
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or \*(Lqold line by line\*(Lq mode, then this character is taken to
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The initial value for the lnext character is taken to be
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character is typed, a
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is sent to the remote host.
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The initial value for the quit character is taken to be
826
or \*(Lqold line by line\*(Lq mode, then this character is taken to
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The initial value for the reprint character is taken to be
835
This is the rlogin mode escape character. Setting it enables rlogin
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command-line option (q.v.)
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.Dv TELNET TOGGLE-FLOW-CONTROL
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option has been enabled,
843
then this character is taken to
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The initial value for the kill character is taken to be
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.Dv TELNET TOGGLE-FLOW-CONTROL
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option has been enabled,
855
then this character is taken to
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The initial value for the kill character is taken to be
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character is typed, a
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is sent to the remote host.
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The initial value for the suspend character is taken to be
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This is the file to which the output, caused by
890
will be written. If it is set to
892
then tracing information will be written to standard output (the default).
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or \*(Lqold line by line\*(Lq mode, then this character is taken to
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The initial value for the worderase character is taken to be
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command (Set Local Characters) is used to set
916
or change the state of the the special
920
been enabled. Special characters are characters that get
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commands sequences (like
927
or line editing characters (like
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By default, the local special characters are exported.
934
Verify the current settings for the current special characters.
935
The remote side is requested to send all the current special
936
character settings, and if there are any discrepancies with
937
the local side, the local side will switch to the remote value.
939
Switch to the local defaults for the special characters. The
940
local default characters are those of the local terminal at
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Switch to the remote defaults for the special characters.
946
The remote default characters are those of the remote system
949
connection was established.
951
Prints out help information for the
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Show the current status of
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This includes the name of the remote host, if any, as well as the
960
.It Ic toggle Ar arguments ...
965
various flags that control how
968
These flags may be set explicitly to
977
More than one flag may be toggled at once.
978
The state of these flags may be examined with the
984
Turns on debugging for the authentication code. This flag only exists
985
if authentication support is enabled.
997
characters are recognized (and transformed into
1003
refuses to display any data on the user's terminal
1004
until the remote system acknowledges (via a
1005
.Dv TELNET TIMING MARK
1007
that it has processed those
1010
The initial value for this toggle is
1012
if the terminal user had not
1013
done an "stty noflsh", otherwise
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option is negotiated, by
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default the actual encryption (decryption) of the data
1022
stream does not start automatically. The autoencrypt
1023
(autodecrypt) command states that encryption of the
1024
output (input) stream should be enabled as soon as
1027
Note that this flag exists only if encryption support is enabled.
1029
If the remote side supports the
1030
.Dv TELNET AUTHENTICATION
1033
attempts to use it to perform automatic authentication. If the
1034
.Dv TELNET AUTHENTICATION
1035
option is not supported, the user's login name is propagated using the
1038
Setting this flag is the same as specifying the
1042
command or on the command line.
1050
then when either the
1054
characters is typed (see
1056
above for descriptions of the
1060
characters), the resulting
1062
sequence sent is followed by the
1067
cause the remote system to begin throwing away all previously
1068
typed input until both of the
1070
sequences have been read and acted upon.
1071
The initial value of this toggle is
1074
Enable or disable the
1076
option on both input and output.
1078
Enable or disable the
1082
Enable or disable the
1088
then carriage returns will be sent as
1092
then carriage returns will be send as
1094
The initial value for this toggle is
1097
Toggle carriage return mode.
1098
When this mode is enabled, most carriage return characters received from
1099
the remote host will be mapped into a carriage return followed by
1101
This mode does not affect those characters typed by the user, only
1102
those received from the remote host.
1103
This mode is not very useful unless the remote host
1104
only sends carriage return, but never line feed.
1105
The initial value for this toggle is
1108
Toggles socket level debugging (useful only to the
1110
The initial value for this toggle is
1113
Turns on debugging information for the encryption code.
1114
Note that this flag only exists if encryption support is available.
1127
above) are recognized locally, and transformed into (hopefully) appropriate
1140
The initial value for this toggle is
1142
in \*(Lqold line by line\*(Rq mode,
1145
in \*(Lqcharacter at a time\*(Rq mode.
1148
option is enabled, the value of
1150
is ignored, and assumed to always be
1154
has ever been enabled, then
1168
Toggles the display of all network data (in hexadecimal format).
1169
The initial value for this toggle is
1172
Toggles the display of some internal
1174
protocol processing (having to do with
1177
The initial value for this toggle is
1182
toggle is enabled, if
1184
is enabled the output from the
1186
command will be formatted in a more user-readable format.
1187
Spaces are put between each character in the output, and the
1190
escape sequences are preceded by a '*' to aid in locating them.
1192
When the skiprc toggle is
1195
does not read the telnetrc files. The initial value for this toggle is
1198
Toggles the display of all terminal data (in hexadecimal format).
1199
The initial value for this toggle is
1201
.It Ic verbose_encrypt
1207
prints out a message each time encryption is enabled or
1208
disabled. The initial value for this toggle is
1210
This flag only exists if encryption support is available.
1219
This command only works when the user is using the
1221
.It Ic \&! Op Ar command
1222
Execute a single command in a subshell on the local
1225
is omitted, then an interactive subshell is invoked.
1226
.It Ic \&? Op Ar command
1227
Get help. With no arguments,
1229
prints a help summary.
1230
If a command is specified,
1232
will print the help information for just that command.
1242
environment variables.
1243
Other environment variables may be propagated
1244
to the other side via the
1248
.Bl -tag -width /etc/telnetrc -compact
1249
.It Pa /etc/telnetrc
1250
global telnet startup values
1252
user customized telnet startup values
1261
On some remote systems, echo has to be turned off manually when in
1262
\*(Lqold line by line\*(Rq mode.
1264
In \*(Lqold line by line\*(Rq mode or
1268
character is only recognized (and sent to the remote system)
1269
when it is the first character on a line.
1271
The source code is not comprehensible.
added
removed
.pc/020-from_18_to_24.diff/telnet/telnet.1
