telnet.1
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- ." 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.
- ." 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.
- ."
- ." @(#)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.
- If the remote side also supports the concept of
- suspending a user's session for later reattachment,
- the logout argument indicates that you
- should terminate the session immediately.
- .It Ic mode Ar type
- .Ar Type
- is one of several options, depending on the state of the
- .Tn TELNET
- session.
- The remote host is asked for permission to go into the requested mode.
- If the remote host is capable of entering that mode, the requested
- mode will be entered.
- .Bl -tag -width Ar
- .It Ic character
- Disable the
- .Dv TELNET LINEMODE
- option, or, if the remote side does not understand the
- .Dv LINEMODE
- option, then enter *(Lqcharacter at a time*(Lq mode.
- .It Ic line
- Enable the
- .Dv TELNET LINEMODE
- option, or, if the remote side does not understand the
- .Dv LINEMODE
- option, then attempt to enter *(Lqold-line-by-line*(Lq mode.
- .It Ic isig Pq Ic -isig
- Attempt to enable (disable) the
- .Dv TRAPSIG
- mode of the
- .Dv LINEMODE
- option.
- This requires that the
- .Dv LINEMODE
- option be enabled.
- .It Ic edit Pq Ic -edit
- Attempt to enable (disable) the
- .Dv EDIT
- mode of the
- .Dv LINEMODE
- option.
- This requires that the
- .Dv LINEMODE
- option be enabled.
- .It Ic softtabs Pq Ic -softtabs
- Attempt to enable (disable) the
- .Dv SOFT_TAB
- mode of the
- .Dv LINEMODE
- option.
- This requires that the
- .Dv LINEMODE
- option be enabled.
- .ne 1i
- .It Ic litecho Pq Ic -litecho
- Attempt to enable (disable) the
- .Dv LIT_ECHO
- mode of the
- .Dv LINEMODE
- option.
- This requires that the
- .Dv LINEMODE
- option be enabled.
- .It Ic &?
- Prints out help information for the
- .Ic mode
- command.
- .El
- .It Xo
- .Ic open Ar host
- .Oo Op Fl l
- .Ar user
- .Oc Ns Oo Fl
- .Ar port Oc
- .Xc
- Open a connection to the named host.
- If no port number
- is specified,
- .Nm telnet
- will attempt to contact a
- .Tn TELNET
- server at the default port.
- The host specification may be either a host name (see
- .Xr hosts 5 )
- or an Internet address specified in the *(Lqdot notation*(Rq (see
- .Xr inet 3 ) .
- The
- .Op Fl l
- option may be used to specify the user name
- to be passed to the remote system via the
- .Ev ENVIRON
- option.
- When connecting to a non-standard port,
- .Nm telnet
- omits any automatic initiation of
- .Tn TELNET
- options. When the port number is preceded by a minus sign,
- the initial option negotiation is done.
- After establishing a connection, the file
- .Pa &.telnetrc
- in the
- users home directory is opened. Lines beginning with a # are
- comment lines. Blank lines are ignored. Lines that begin
- without white space are the start of a machine entry. The
- first thing on the line is the name of the machine that is
- being connected to. The rest of the line, and successive
- lines that begin with white space are assumed to be
- .Nm telnet
- commands and are processed as if they had been typed
- in manually to the
- .Nm telnet
- command prompt.
- .It Ic quit
- Close any open
- .Tn TELNET
- session and exit
- .Nm telnet .
- An end of file (in command mode) will also close a session and exit.
- .It Ic send Ar arguments
- Sends one or more special character sequences to the remote host.
- The following are the arguments which may be specified
- (more than one argument may be specified at a time):
- .Pp
- .Bl -tag -width escape
- .It Ic abort
- Sends the
- .Dv TELNET ABORT
- (Abort
- processes)
- sequence.
- .It Ic ao
- Sends the
- .Dv TELNET AO
- (Abort Output) sequence, which should cause the remote system to flush
- all output
- .Em from
- the remote system
- .Em to
- the user's terminal.
- .It Ic ayt
- Sends the
- .Dv TELNET AYT
- (Are You There)
- sequence, to which the remote system may or may not choose to respond.
- .It Ic brk
- Sends the
- .Dv TELNET BRK
- (Break) sequence, which may have significance to the remote
- system.
- .It Ic ec
- Sends the
- .Dv TELNET EC
- (Erase Character)
- sequence, which should cause the remote system to erase the last character
- entered.
- .It Ic el
- Sends the
- .Dv TELNET EL
- (Erase Line)
- sequence, which should cause the remote system to erase the line currently
- being entered.
- .It Ic eof
- Sends the
- .Dv TELNET EOF
- (End Of File)
- sequence.
- .It Ic eor
- Sends the
- .Dv TELNET EOR
- (End of Record)
- sequence.
- .It Ic escape
- Sends the current
- .Nm telnet
- escape character (initially *(Lq^*(Rq).
- .It Ic ga
- Sends the
- .Dv TELNET GA
- (Go Ahead)
- sequence, which likely has no significance to the remote system.
- .It Ic getstatus
- If the remote side supports the
- .Dv TELNET STATUS
- command,
- .Ic getstatus
- will send the subnegotiation to request that the server send
- its current option status.
- .ne 1i
- .It Ic ip
- Sends the
- .Dv TELNET IP
- (Interrupt Process) sequence, which should cause the remote
- system to abort the currently running process.
- .It Ic nop
- Sends the
- .Dv TELNET NOP
- (No OPeration)
- sequence.
- .It Ic susp
- Sends the
- .Dv TELNET SUSP
- (SUSPend process)
- sequence.
- .It Ic synch
- Sends the
- .Dv TELNET SYNCH
- sequence.
- This sequence causes the remote system to discard all previously typed
- (but not yet read) input.
- This sequence is sent as
- .Tn TCP
- urgent
- data (and may not work if the remote system is a
- .Bx 4.2
- system -- if
- it doesn't work, a lower case *(Lqr*(Rq may be echoed on the terminal).
- .It Ic do Ar cmd
- .It Ic dont Ar cmd
- .It Ic will Ar cmd
- .It Ic wont Ar cmd
- Sends the
- .Dv TELNET DO
- .Ar cmd
- sequence.
- .Ar Cmd
- can be either a decimal number between 0 and 255,
- or a symbolic name for a specific
- .Dv TELNET
- command.
- .Ar Cmd
- can also be either
- .Ic help
- or
- .Ic &?
- to print out help information, including
- a list of known symbolic names.
- .It Ic &?
- Prints out help information for the
- .Ic send
- command.
- .El
- .It Ic set Ar argument value
- .It Ic unset Ar argument value
- The
- .Ic set
- command will set any one of a number of
- .Nm telnet
- variables to a specific value or to
- .Dv TRUE .
- The special value
- .Ic off
- turns off the function associated with
- the variable, this is equivalent to using the
- .Ic unset
- command.
- The
- .Ic unset
- command will disable or set to
- .Dv FALSE
- any of the specified functions.
- The values of variables may be interrogated with the
- .Ic display
- command.
- The variables which may be set or unset, but not toggled, are
- listed here. In addition, any of the variables for the
- .Ic toggle
- command may be explicitly set or unset using
- the
- .Ic set
- and
- .Ic unset
- commands.
- .Bl -tag -width escape
- .It Ic ayt
- If
- .Tn TELNET
- is in localchars mode, or
- .Dv LINEMODE
- is enabled, and the status character is typed, a
- .Dv TELNET AYT
- sequence (see
- .Ic send ayt
- preceding) is sent to the
- remote host. The initial value for the "Are You There"
- character is the terminal's status character.
- .It Ic echo
- This is the value (initially *(Lq^E*(Rq) which, when in
- *(Lqline by line*(Rq mode, toggles between doing local echoing
- of entered characters (for normal processing), and suppressing
- echoing of entered characters (for entering, say, a password).
- .It Ic eof
- If
- .Nm telnet
- is operating in
- .Dv LINEMODE
- or *(Lqold line by line*(Rq mode, entering this character
- as the first character on a line will cause this character to be
- sent to the remote system.
- The initial value of the eof character is taken to be the terminal's
- .Ic eof
- character.
- .It Ic erase
- If
- .Nm telnet
- is in
- .Ic localchars
- mode (see
- .Ic toggle
- .Ic localchars
- below),
- .Sy and
- if
- .Nm telnet
- is operating in *(Lqcharacter at a time*(Rq mode, then when this
- character is typed, a
- .Dv TELNET EC
- sequence (see
- .Ic send
- .Ic ec
- above)
- is sent to the remote system.
- The initial value for the erase character is taken to be
- the terminal's
- .Ic erase
- character.
- .It Ic escape
- This is the
- .Nm telnet
- escape character (initially *(Lq^[*(Rq) which causes entry
- into
- .Nm telnet
- command mode (when connected to a remote system).
- .It Ic flushoutput
- If
- .Nm telnet
- is in
- .Ic localchars
- mode (see
- .Ic toggle
- .Ic localchars
- below)
- and the
- .Ic flushoutput
- character is typed, a
- .Dv TELNET AO
- sequence (see
- .Ic send
- .Ic ao
- above)
- is sent to the remote host.
- The initial value for the flush character is taken to be
- the terminal's
- .Ic flush
- character.
- .It Ic forw1
- .It Ic forw2
- If
- .Tn TELNET
- is operating in
- .Dv LINEMODE ,
- these are the
- characters that, when typed, cause partial lines to be
- forwarded to the remote system. The initial value for
- the forwarding characters are taken from the terminal's
- eol and eol2 characters.
- .It Ic interrupt
- If
- .Nm telnet
- is in
- .Ic localchars
- mode (see
- .Ic toggle
- .Ic localchars
- below)
- and the
- .Ic interrupt
- character is typed, a
- .Dv TELNET IP
- sequence (see
- .Ic send
- .Ic ip
- above)
- is sent to the remote host.
- The initial value for the interrupt character is taken to be
- the terminal's
- .Ic intr
- character.
- .It Ic kill
- If
- .Nm telnet
- is in
- .Ic localchars
- mode (see
- .Ic toggle
- .Ic localchars
- below),
- .Ic and
- if
- .Nm telnet
- is operating in *(Lqcharacter at a time*(Rq mode, then when this
- character is typed, a
- .Dv TELNET EL
- sequence (see
- .Ic send
- .Ic el
- above)
- is sent to the remote system.
- The initial value for the kill character is taken to be
- the terminal's
- .Ic kill
- character.
- .It Ic lnext
- If
- .Nm telnet
- is operating in
- .Dv LINEMODE
- or *(Lqold line by line*(Lq mode, then this character is taken to
- be the terminal's
- .Ic lnext
- character.
- The initial value for the lnext character is taken to be
- the terminal's
- .Ic lnext
- character.
- .It Ic quit
- If
- .Nm telnet
- is in
- .Ic localchars
- mode (see
- .Ic toggle
- .Ic localchars
- below)
- and the
- .Ic quit
- character is typed, a
- .Dv TELNET BRK
- sequence (see
- .Ic send
- .Ic brk
- above)
- is sent to the remote host.
- The initial value for the quit character is taken to be
- the terminal's
- .Ic quit
- character.
- .It Ic reprint
- If
- .Nm telnet
- is operating in
- .Dv LINEMODE
- or *(Lqold line by line*(Lq mode, then this character is taken to
- be the terminal's
- .Ic reprint
- character.
- The initial value for the reprint character is taken to be
- the terminal's
- .Ic reprint
- character.
- .It Ic rlogin
- This is the rlogin escape character.
- If set, the normal
- .Tn TELNET
- escape character is ignored unless it is
- preceded by this character at the beginning of a line.
- This character, at the beginning of a line followed by
- a "." closes the connection; when followed by a ^Z it
- suspends the telnet command. The initial state is to
- disable the rlogin escape character.
- .It Ic start
- If the
- .Dv TELNET TOGGLE-FLOW-CONTROL
- option has been enabled,
- then this character is taken to
- be the terminal's
- .Ic start
- character.
- The initial value for the kill character is taken to be
- the terminal's
- .Ic start
- character.
- .It Ic stop
- If the
- .Dv TELNET TOGGLE-FLOW-CONTROL
- option has been enabled,
- then this character is taken to
- be the terminal's
- .Ic stop
- character.
- The initial value for the kill character is taken to be
- the terminal's
- .Ic stop
- character.
- .It Ic susp
- If
- .Nm telnet
- is in
- .Ic localchars
- mode, or
- .Dv LINEMODE
- is enabled, and the
- .Ic suspend
- character is typed, a
- .Dv TELNET SUSP
- sequence (see
- .Ic send
- .Ic susp
- above)
- is sent to the remote host.
- The initial value for the suspend character is taken to be
- the terminal's
- .Ic suspend
- character.
- .ne 1i
- .It Ic tracefile
- This is the file to which the output, caused by
- .Ic netdata
- or
- .Ic option
- tracing being
- .Dv TRUE ,
- will be written. If it is set to
- .Dq Fl ,
- then tracing information will be written to standard output (the default).
- .It Ic worderase
- If
- .Nm telnet
- is operating in
- .Dv LINEMODE
- or *(Lqold line by line*(Lq mode, then this character is taken to
- be the terminal's
- .Ic worderase
- character.
- The initial value for the worderase character is taken to be
- the terminal's
- .Ic worderase
- character.
- .It Ic &?
- Displays the legal
- .Ic set
- .Pq Ic unset
- commands.
- .El
- .It Ic slc Ar state
- The
- .Ic slc
- command (Set Local Characters) is used to set
- or change the state of the the special
- characters when the
- .Dv TELNET LINEMODE
- option has
- been enabled. Special characters are characters that get
- mapped to
- .Tn TELNET
- commands sequences (like
- .Ic ip
- or
- .Ic quit )
- or line editing characters (like
- .Ic erase
- and
- .Ic kill ) .
- By default, the local special characters are exported.
- .Bl -tag -width Fl
- .It Ic check
- Verify the current settings for the current special characters.
- The remote side is requested to send all the current special
- character settings, and if there are any discrepancies with
- the local side, the local side will switch to the remote value.
- .It Ic export
- Switch to the local defaults for the special characters. The
- local default characters are those of the local terminal at
- the time when
- .Nm telnet
- was started.
- .It Ic import
- Switch to the remote defaults for the special characters.
- The remote default characters are those of the remote system
- at the time when the
- .Tn TELNET
- connection was established.
- .It Ic &?
- Prints out help information for the
- .Ic slc
- command.
- .El
- .It Ic status
- Show the current status of
- .Nm telnet .
- This includes the peer one is connected to, as well
- as the current mode.
- .It Ic toggle Ar arguments ...
- Toggle (between
- .Dv TRUE
- and
- .Dv FALSE )
- various flags that control how
- .Nm telnet
- responds to events.
- These flags may be set explicitly to
- .Dv TRUE
- or
- .Dv FALSE
- using the
- .Ic set
- and
- .Ic unset
- commands listed above.
- More than one argument may be specified.
- The state of these flags may be interrogated with the
- .Ic display
- command.
- Valid arguments are:
- .Bl -tag -width Ar
- .It Ic authdebug
- Turns on debugging information for the authentication code.
- .It Ic autoflush
- If
- .Ic autoflush
- and
- .Ic localchars
- are both
- .Dv TRUE ,
- then when the
- .Ic ao ,
- or
- .Ic quit
- characters are recognized (and transformed into
- .Tn TELNET
- sequences; see
- .Ic set
- above for details),
- .Nm telnet
- refuses to display any data on the user's terminal
- until the remote system acknowledges (via a
- .Dv TELNET TIMING MARK
- option)
- that it has processed those
- .Tn TELNET
- sequences.
- The initial value for this toggle is
- .Dv TRUE
- if the terminal user had not
- done an "stty noflsh", otherwise
- .Dv FALSE
- (see
- .Xr stty 1 ) .
- .It Ic autodecrypt
- When the
- .Dv TELNET ENCRYPT
- option is negotiated, by
- default the actual encryption (decryption) of the data
- stream does not start automatically. The autoencrypt
- (autodecrypt) command states that encryption of the
- output (input) stream should be enabled as soon as
- possible.
- .sp
- .Pp
- Note: Because of export controls, the
- .Dv TELNET ENCRYPT
- option is not supported outside the United States and Canada.
- .It Ic autologin
- If the remote side supports the
- .Dv TELNET AUTHENTICATION
- option
- .Tn TELNET
- attempts to use it to perform automatic authentication. If the
- .Dv AUTHENTICATION
- option is not supported, the user's login
- name are propagated through the
- .Dv TELNET ENVIRON
- option.
- This command is the same as specifying
- .Ar a
- option on the
- .Ic open
- command.
- .It Ic autosynch
- If
- .Ic autosynch
- and
- .Ic localchars
- are both
- .Dv TRUE ,
- then when either the
- .Ic intr
- or
- .Ic quit
- characters is typed (see
- .Ic set
- above for descriptions of the
- .Ic intr
- and
- .Ic quit
- characters), the resulting
- .Tn TELNET
- sequence sent is followed by the
- .Dv TELNET SYNCH
- sequence.
- This procedure
- .Ic should
- cause the remote system to begin throwing away all previously
- typed input until both of the
- .Tn TELNET
- sequences have been read and acted upon.
- The initial value of this toggle is
- .Dv FALSE .
- .It Ic binary
- Enable or disable the
- .Dv TELNET BINARY
- option on both input and output.
- .It Ic inbinary
- Enable or disable the
- .Dv TELNET BINARY
- option on input.
- .It Ic outbinary
- Enable or disable the
- .Dv TELNET BINARY
- option on output.
- .It Ic crlf
- If this is
- .Dv TRUE ,
- then carriage returns will be sent as
- .Li <CR><LF> .
- If this is
- .Dv FALSE ,
- then carriage returns will be send as
- .Li <CR><NUL> .
- The initial value for this toggle is
- .Dv FALSE .
- .It Ic crmod
- Toggle carriage return mode.
- When this mode is enabled, most carriage return characters received from
- the remote host will be mapped into a carriage return followed by
- a line feed.
- This mode does not affect those characters typed by the user, only
- those received from the remote host.
- This mode is not very useful unless the remote host
- only sends carriage return, but never line feed.
- The initial value for this toggle is
- .Dv FALSE .
- .It Ic debug
- Toggles socket level debugging (useful only to the
- .Ic super user ) .
- The initial value for this toggle is
- .Dv FALSE .
- .It Ic encdebug
- Turns on debugging information for the encryption code.
- .It Ic localchars
- If this is
- .Dv TRUE ,
- then the
- .Ic flush ,
- .Ic interrupt ,
- .Ic quit ,
- .Ic erase ,
- and
- .Ic kill
- characters (see
- .Ic set
- above) are recognized locally, and transformed into (hopefully) appropriate
- .Tn TELNET
- control sequences
- (respectively
- .Ic ao ,
- .Ic ip ,
- .Ic brk ,
- .Ic ec ,
- and
- .Ic el ;
- see
- .Ic send
- above).
- The initial value for this toggle is
- .Dv TRUE
- in *(Lqold line by line*(Rq mode,
- and
- .Dv FALSE
- in *(Lqcharacter at a time*(Rq mode.
- When the
- .Dv LINEMODE
- option is enabled, the value of
- .Ic localchars
- is ignored, and assumed to always be
- .Dv TRUE .
- If
- .Dv LINEMODE
- has ever been enabled, then
- .Ic quit
- is sent as
- .Ic abort ,
- and
- .Ic eof and
- .B suspend
- are sent as
- .Ic eof and
- .Ic susp ,
- see
- .Ic send
- above).
- .It Ic netdata
- Toggles the display of all network data (in hexadecimal format).
- The initial value for this toggle is
- .Dv FALSE .
- .It Ic options
- Toggles the display of some internal
- .Nm telnet
- protocol processing (having to do with
- .Tn TELNET
- options).
- The initial value for this toggle is
- .Dv FALSE .
- .ne 1i
- .It Ic prettydump
- When the
- .Ic netdata
- toggle is enabled, if
- .Ic prettydump
- is enabled the output from the
- .Ic netdata
- command will be formatted in a more user readable format.
- Spaces are put between each character in the output, and the
- beginning of any
- .Tn TELNET
- escape sequence is preceded by a '*' to aid in locating them.
- .It Ic skiprc
- When the skiprc toggle is
- .Dv TRUE ,
- .Tn TELNET
- skips the reading of the
- .Pa &.telnetrc
- file in the users home
- directory when connections are opened. The initial
- value for this toggle is
- .Dv FALSE.
- .It Ic termdata
- Toggles the display of all terminal data (in hexadecimal format).
- The initial value for this toggle is
- .Dv FALSE .
- .It Ic verbose_encrypt
- When the
- .Ic verbose_encrypt
- toggle is
- .Dv TRUE ,
- .Tn TELNET
- prints out a message each time encryption is enabled or
- disabled. The initial value for this toggle is
- .Dv FALSE.
- Note: Because of export controls, data encryption
- is not supported outside of the United States and Canada.
- .It Ic &?
- Displays the legal
- .Ic toggle
- commands.
- .El
- .It Ic z
- Suspend
- .Nm telnet .
- This command only works when the user is using the
- .Xr csh 1 .
- .It Ic &! Op Ar command
- Execute a single command in a subshell on the local
- system. If
- .Ic command
- is omitted, then an interactive
- subshell is invoked.
- .It Ic &? Op Ar command
- Get help. With no arguments,
- .Nm telnet
- prints a help summary.
- If a command is specified,
- .Nm telnet
- will print the help information for just that command.
- .El
- .Sh ENVIRONMENT
- .Nm Telnet
- uses at least the
- .Ev HOME ,
- .Ev SHELL ,
- .Ev DISPLAY ,
- and
- .Ev TERM
- environment variables.
- Other environment variables may be propagated
- to the other side via the
- .Dv TELNET ENVIRON
- option.
- .Sh FILES
- .Bl -tag -width ~/.telnetrc -compact
- .It Pa ~/.telnetrc
- user customized telnet startup values
- .El
- .Sh HISTORY
- The
- .Nm Telnet
- command appeared in
- .Bx 4.2 .
- .Sh NOTES
- .Pp
- On some remote systems, echo has to be turned off manually when in
- *(Lqold line by line*(Rq mode.
- .Pp
- In *(Lqold line by line*(Rq mode or
- .Dv LINEMODE
- the terminal's
- .Ic eof
- character is only recognized (and sent to the remote system)
- when it is the first character on a line.