telnet.1

压缩包中包含LINUX下多个命令的源码

.\" Copyright (c) 1983, 1990, 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.
.\" 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.
.\"
.\"	@(#)telnet.1	8.6 (Berkeley) 6/1/94
.\"
.Dd June 1, 1994
.Dt TELNET 1
.Os BSD 4.2
.Sh NAME
.Nm telnet
.Nd user interface to the
.Tn TELNET
protocol
.Sh SYNOPSIS
.Nm telnet
.Op Fl 8EFKLacdfrx
.Op Fl S Ar tos
.Op Fl X Ar authtype
.Op Fl e Ar escapechar
.Op Fl k Ar realm
.Op Fl l Ar user
.Op Fl n Ar tracefile
.Oo
.Ar host
.Op port
.Oc
.Sh DESCRIPTION
The
.Nm telnet
command
is used to communicate with another host using the
.Tn TELNET
protocol.
If
.Nm telnet
is invoked without the
.Ar host
argument, it enters command mode,
indicated by its prompt
.Pq Nm telnet\&> .
In this mode, it accepts and executes the commands listed below.
If it is invoked with arguments, it performs an
.Ic open
command with those arguments.
.Pp
Options:
.Bl -tag -width indent
.It Fl 8
Specifies an 8-bit data path.  This causes an attempt to
negotiate the
.Dv TELNET BINARY
option on both input and output.
.It Fl E
Stops any character from being recognized as an escape character.
.It Fl F
If Kerberos V5 authentication is being used, the
.Fl F
option allows the local credentials to be forwarded
to the remote system, including any credentials that
have already been forwarded into the local environment.
.It Fl K
Specifies no automatic login to the remote system.
.It Fl L
Specifies an 8-bit data path on output.  This causes the
BINARY option to be negotiated on output.
.It Fl S Ar tos
Sets the IP type-of-service (TOS) option for the telnet
connection to the value
.Ar tos,
which can be a numeric TOS value
or, on systems that support it, a symbolic
TOS name found in the /etc/iptos file.
.It Fl X Ar atype
Disables the
.Ar atype
type of authentication.
.It Fl a
Attempt automatic login.
Currently, this sends the user name via the
.Ev USER
variable
of the
.Ev ENVIRON
option if supported by the remote system.
The name used is that of the current user as returned by
.Xr getlogin 2
if it agrees with the current user ID,
otherwise it is the name associated with the user ID.
.It Fl c
Disables the reading of the user's
.Pa \&.telnetrc
file.  (See the
.Ic toggle skiprc
command on this man page.)
.It Fl d
Sets the initial value of the
.Ic debug
toggle to
.Dv TRUE
.It Fl e Ar escape char
Sets the initial
.Nm
.Nm telnet
escape character to
.Ar escape char.
If
.Ar escape char
is omitted, then
there will be no escape character.
.It Fl f
If Kerberos V5 authentication is being used, the
.Fl f
option allows the local credentials to be forwarded to the remote system.
.ne 1i
.It Fl k Ar realm
If Kerberos authentication is being used, the
.Fl k
option requests that telnet obtain tickets for the remote host in
realm realm instead of the remote host's realm, as determined
by
.Xr krb_realmofhost 3 .
.It Fl l Ar user
When connecting to the remote system, if the remote system
understands the
.Ev ENVIRON
option, then
.Ar user
will be sent to the remote system as the value for the variable USER.
This option implies the
.Fl a
option.
This option may also be used with the
.Ic open
command.
.It Fl n Ar tracefile
Opens
.Ar tracefile
for recording trace information.
See the
.Ic set tracefile
command below.
.It Fl r
Specifies a user interface similar to
.Xr rlogin 1 .
In this
mode, the escape character is set to the tilde (~) character,
unless modified by the -e option.
.It Fl x
Turns on encryption of the data stream if possible.  This
option is not available outside of the United States and
Canada.
.It Ar host
Indicates the official name, an alias, or the Internet address
of a remote host.
.It Ar port
Indicates a port number (address of an application).  If a number is
not specified, the default
.Nm telnet
port is used.
.El
.Pp
When in rlogin mode, a line of the form ~.  disconnects from the
remote host; ~ is the telnet escape character.
Similarly, the line ~^Z suspends the telnet session.
The line ~^] escapes to the normal telnet escape prompt.
.Pp
Once a connection has been opened,
.Nm telnet
will attempt to enable the
.Dv TELNET LINEMODE
option.
If this fails, then
.Nm telnet
will revert to one of two input modes:
either \*(Lqcharacter at a time\*(Rq
or \*(Lqold line by line\*(Rq
depending on what the remote system supports.
.Pp
When
.Dv LINEMODE
is enabled, character processing is done on the
local system, under the control of the remote system.  When input
editing or character echoing is to be disabled, the remote system
will relay that information.  The remote system will also relay
changes to any special characters that happen on the remote
system, so that they can take effect on the local system.
.Pp
In \*(Lqcharacter at a time\*(Rq mode, most
text typed is immediately sent to the remote host for processing.
.Pp
In \*(Lqold line by line\*(Rq mode, all text is echoed locally,
and (normally) only completed lines are sent to the remote host.
The \*(Lqlocal echo character\*(Rq (initially \*(Lq^E\*(Rq) may be used
to turn off and on the local echo
(this would mostly be used to enter passwords
without the password being echoed).
.Pp
If the
.Dv LINEMODE
option is enabled, or if the
.Ic localchars
toggle is
.Dv TRUE
(the default for \*(Lqold line by line\*(Lq; see below),
the user's
.Ic quit  ,
.Ic intr ,
and
.Ic flush
characters are trapped locally, and sent as
.Tn TELNET
protocol sequences to the remote side.
If
.Dv LINEMODE
has ever been enabled, then the user's
.Ic susp
and
.Ic eof
are also sent as
.Tn TELNET
protocol sequences,
and
.Ic quit
is sent as a
.Dv TELNET ABORT
instead of
.Dv BREAK
There are options (see
.Ic toggle
.Ic autoflush
and
.Ic toggle
.Ic autosynch
below)
which cause this action to flush subsequent output to the terminal
(until the remote host acknowledges the
.Tn TELNET
sequence) and flush previous terminal input
(in the case of
.Ic quit
and
.Ic intr  ) .
.Pp
While connected to a remote host,
.Nm telnet
command mode may be entered by typing the
.Nm telnet
\*(Lqescape character\*(Rq (initially \*(Lq^]\*(Rq).
When in command mode, the normal terminal editing conventions are available.
.Pp
The following
.Nm telnet
commands are available.
Only enough of each command to uniquely identify it need be typed
(this is also true for arguments to the
.Ic mode  ,
.Ic set ,
.Ic toggle  ,
.Ic unset ,
.Ic slc  ,
.Ic environ ,
and
.Ic display
commands).
.Pp
.Bl -tag -width "mode type"
.It Ic auth Ar argument ...
The auth command manipulates the information sent through the
.Dv TELNET AUTHENTICATE
option.  Valid arguments for the
auth command are as follows:
.Bl -tag -width "disable type"
.It Ic disable Ar type
Disables the specified type of authentication.  To
obtain a list of available types, use the
.Ic auth disable \&?
command.
.It Ic enable Ar type
Enables the specified type of authentication.  To
obtain a list of available types, use the
.Ic auth enable \&?
command.
.It Ic status
Lists the current status of the various types of
authentication.
.El
.It Ic close
Close a
.Tn TELNET
session and return to command mode.
.It Ic display Ar argument ...
Displays all, or some, of the
.Ic set
and
.Ic toggle
values (see below).
.It Ic encrypt Ar argument ...
The encrypt command manipulates the information sent through the
.Dv TELNET ENCRYPT
option.
.Pp
Note:  Because of export controls, the
.Dv TELNET ENCRYPT
option is not supported outside of the United States and Canada.
.Pp
Valid arguments for the encrypt command are as follows:
.Bl -tag -width Ar
.It Ic disable Ar type Ic [input|output]
Disables the specified type of encryption.  If you
omit the input and output, both input and output
are disabled.  To obtain a list of available
types, use the
.Ic encrypt disable \&?
command.
.It Ic enable Ar type Ic [input|output]
Enables the specified type of encryption.  If you
omit input and output, both input and output are
enabled.  To obtain a list of available types, use the
.Ic encrypt enable \&?
command.
.It Ic input
This is the same as the
.Ic encrypt start input
command.
.It Ic -input
This is the same as the
.Ic encrypt stop input
command.
.It Ic output
This is the same as the
.Ic encrypt start output
command.
.It Ic -output
This is the same as the
.Ic encrypt stop output
command.
.It Ic start Ic [input|output]
Attempts to start encryption.  If you omit
.Ic input
and
.Ic output,
both input and output are enabled.  To
obtain a list of available types, use the
.Ic encrypt enable \&?
command.
.It Ic status
Lists the current status of encryption.
.It Ic stop Ic [input|output]
Stops encryption.  If you omit input and output,
encryption is on both input and output.
.It Ic type Ar type
Sets the default type of encryption to be used
with later
.Ic encrypt start
or
.Ic encrypt stop
commands.
.El
.It Ic environ Ar arguments...
The
.Ic environ
command is used to manipulate the
the variables that my be sent through the
.Dv TELNET ENVIRON
option.
The initial set of variables is taken from the users
environment, with only the
.Ev DISPLAY
and
.Ev PRINTER
variables being exported by default.
The
.Ev USER
variable is also exported if the
.Fl a
or
.Fl l
options are used.
.br
Valid arguments for the
.Ic environ
command are:
.Bl -tag -width Fl
.It Ic define Ar variable value
Define the variable
.Ar variable
to have a value of
.Ar value.
Any variables defined by this command are automatically exported.
The
.Ar value
may be enclosed in single or double quotes so
that tabs and spaces may be included.
.It Ic undefine Ar variable
Remove
.Ar variable
from the list of environment variables.
.It Ic export Ar variable
Mark the variable
.Ar variable
to be exported to the remote side.
.It Ic unexport Ar variable
Mark the variable
.Ar variable
to not be exported unless
explicitly asked for by the remote side.
.It Ic list
List the current set of environment variables.
Those marked with a
.Cm *
will be sent automatically,
other variables will only be sent if explicitly requested.
.It Ic \&?
Prints out help information for the
.Ic environ
command.
.El
.It Ic logout
Sends the
.Dv TELNET LOGOUT
option to the remote side.
This command is similar to a
.Ic close
command; however, if the remote side does not support the
.Dv LOGOUT
option, nothing happens.
If, however, the remote side does support the
.Dv LOGOUT
option, this command should cause the remote side to close the
.Tn TELNET
connection.