The commands described in this section are available with
telnet. It is necessary to type only enough of each command to
uniquely identify it. (This is also true for arguments to the mode,
set, toggle, unset, environ, and display
commands.)
auth argument ...
The
auth command manipulates the information sent
through the
TELNET AUTHENTICATE option. Valid arguments for the
auth command are as follows:
disable type
Disables the specified type of authentication. To obtain
a list of available types, use the auth disable ? command.
enable type
Enables the specified type of authentication. To obtain a
list of available types, use the auth enable ? command.
status
Lists the current status of the various types of
authentication.
open [-l user ] [ [!]
@hop1 [@hop2 ...]@host [ port ]
Open a connection to the named host. If no port number is
specified,
telnet will attempt to contact a
TELNET server at the
default port. The host specification may be either a host name (see
hosts(5)) or an Internet address specified in the "dot
notation" (see
inet(4P) or
inet6(4P)). If the
host
is specified as
@hop1@hop2@host, the connection goes through hosts
hop1 and
hop2, using loose source routing to end at
host.
The
@ symbol is required as a separator between the hosts specified. If
a leading
! is used with IPv4, the connection follows strict source
routing.
The -l option passes the user as the value of the
ENVIRON variable USER to the remote system.
close
Close any open TELNET session and exit
telnet. An EOF (in command mode) will also close a session and
exit.
encrypt
The encrypt command manipulates the information sent
through the
TELNET ENCRYPT option.
Valid arguments for the encrypt command are as follows:
disable type [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 encrypt disable ? command.
enable type [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 encrypt enable ? command.
input
This is the same as the encrypt start input
command.
-input
This is the same as the encrypt stop input
command.
output
This is the same as the encrypt start
output command.
-output
This is the same as the encrypt stop output
command.
start [input|output]
Attempts to start encryption. If you omit input and
output, both input and output are enabled. To obtain a list of available
types, use the encrypt enable ? command.
status
Lists the current status of encryption.
stop [input|output]
Stops encryption. If you omit input and output,
encryption is on both input and output.
type type
Sets the default type of encryption to be used with later
encrypt start or encrypt stop commands.
quit
Same as close.
z
Suspend
telnet. This command only works when the
user is using a shell that supports job control, such as
sh(1).
mode type
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. The argument
type is one of the
following:
character
Disable the TELNET LINEMODE option, or, if the
remote side does not understand the LINEMODE option, then enter
"character at a time" mode.
line
Enable the TELNET LINEMODE option, or, if the
remote side does not understand the LINEMODE option, then attempt to
enter "old-line-by-line" mode.
isig (-isig)
Attempt to enable (disable) the TRAPSIG mode of
the LINEMODE option. This requires that the LINEMODE option be
enabled.
edit (-edit)
Attempt to enable (disable) the EDIT mode of the
LINEMODE option. This requires that the LINEMODE option be
enabled.
softtabs (-softtabs)
Attempt to enable (disable) the SOFT_TAB mode of
the LINEMODE option. This requires that the LINEMODE option be
enabled.
litecho (-litecho)
Attempt to enable (disable) the LIT_ECHO mode of
the LINEMODE option. This requires that the LINEMODE option be
enabled.
?
Prints out help information for the mode
command.
status
Show the current status of telnet. This includes
the peer one is connected to, as well as the current mode.
display
[argument...] Display all, or some, of the
set and toggle values (see toggle
argument...).
?
[command] Get help. With no arguments,
telnet prints a help summary. If a command is specified, telnet
will print the help information for just that command.
send argument...
Send one or more special character sequences to the
remote host. The following are the arguments that can be specified (more than
one argument may be specified at a time):
escape
Send the current telnet escape character
(initially ^]).
synch
Send the TELNET SYNCH sequence. This sequence
discards all previously typed, but not yet read, input on the remote system.
This sequence is sent as TCP urgent data and may not work if the remote
system is a 4.2 BSD system. If it does not work, a lowercase
"r" may be echoed on the terminal.
brk or break
Send the TELNET BRK (Break) sequence, which may
have significance to the remote system.
ip
Send the TELNET IP (Interrupt Process) sequence,
which aborts the currently running process on the remote system.
abort
Send the TELNET ABORT (Abort Process)
sequence.
ao
Send the TELNET AO (Abort Output) sequence, which
flushes all output from the remote system to the user's terminal.
ayt
Send the TELNET AYT (Are You There) sequence, to
which the remote system may or may not respond.
ec
Send the TELNET EC (Erase Character) sequence,
which erases the last character entered.
el
Send the TELNET EL (Erase Line) sequence, which
should cause the remote system to erase the line currently being
entered.
eof
Send the TELNET EOF (End Of File) sequence.
eor
Send the TELNET EOR (End Of Record)
sequence.
ga
Send the TELNET GA (Go Ahead) sequence, which
probably has no significance for the remote system.
getstatus
If the remote side supports the TELNET STATUS
command, getstatus will send the subnegotiation to request that the
server send its current option status.
nop
Send the TELNET NOP (No Operation) sequence.
susp
Send the TELNET SUSP (Suspend Process)
sequence.
do option
dont option
will option
wont option
Send the TELNET protocol option negotiation
indicated. Option may be the text name of the protocol option, or the number
corresponding to the option. The command will be silently ignored if the
option negotiation indicated is not valid in the current state. If the
option is given as help or ?, the list of option names
known is listed. This command is mostly useful for unusual debugging
situations.
?
Print out help information for the send
command.
set argument [value]
unset argument
Set any one of a number of
telnet variables to a
specific value. The special value
off turns off the function associated
with the variable. The values of variables may be interrogated with the
display command. If
value is omitted, the value is taken to be
true, or "on". If the
unset form is used, the value is taken
to be false, or
off. The variables that may be specified are:
echo
This is the value (initially ^E) that, when in
"line by line" mode, toggles between local echoing of entered
characters for normal processing, and suppressing echoing of entered
characters, for example, entering a password.
escape
This is the telnet escape character (initially
^]) that enters telnet command mode when connected to a remote
system.
interrupt
If telnet is in localchars mode (see
toggle, localchars) and the interrupt character is typed,
a TELNET IP sequence (see send and ip) is sent to the
remote host. The initial value for the interrupt character is taken to be the
terminal's intr character.
quit
If telnet is in localchars mode and the
quit character is typed, a TELNET BRK sequence (see send,
brk) is sent to the remote host. The initial value for the quit
character is taken to be the terminal's quit character.
flushoutput
If telnet is in localchars mode and the
flushoutput character is typed, a TELNET AO sequence (see
send, ao) is sent to the remote host. The initial value for the
flush character is taken to be the terminal's flush character.
erase
If telnet is in localchars mode and
operating in "character at a time" mode, then when the erase
character is typed, a TELNET EC sequence (see send,
ec) is sent to the remote system. The initial value for the
erase character is taken to be the terminal's erase
character.
kill
If telnet is in localchars mode and
operating in "character at a time" mode, then when the kill
character is typed, a TELNET EL sequence (see send, el)
is sent to the remote system. The initial value for the kill character
is taken to be the terminal's kill character.
eof
If telnet is operating in "line by
line"/ mode, entering the eof character as the first character on
a line sends this character to the remote system. The initial value of
eof is taken to be the terminal's eof character.
ayt
If telnet is in localchars mode, or
LINEMODE is enabled, and the status character is typed, a TELNET
AYT ("Are You There") sequence is sent to the remote host. (See
send, ayt above.) The initial value for ayt is the
terminal's status character.
forw1
forw2
If telnet is operating in LINEMODE, and the
forw1 or forw2 characters are typed, this causes the forwarding
of partial lines to the remote system. The initial values for the forwarding
characters come from the terminal's eol and eol2
characters.
lnext
If telnet is operating in LINEMODE or
"old line by line" mode, then the lnext character is assumed
to be the terminal's lnext character. The initial value for the
lnext character is taken to be the terminal's lnext
character.
reprint
If telnet is operating in LINEMODE or
"old line by line" mode, then the reprint character is
assumed to be the terminal's reprint character. The initial value for
reprint is taken to be the terminal's reprint character.
rlogin
This is the rlogin escape character. If set, the
normal telnet escape character is ignored, unless it is preceded by
this character at the beginning of a line. The rlogin character, at the
beginning of a line followed by a "." closes the connection.
When followed by a ^Z, the rlogin command suspends the
telnet command. The initial state is to disable the rlogin
escape character.
start
If the TELNET TOGGLE-FLOW-CONTROL option has been
enabled, then the start character is taken to be the terminal's
start character. The initial value for the kill character is
taken to be the terminal's start character.
stop
If the TELNET TOGGLE-FLOW-CONTROL option has been
enabled, then the stop character is taken to be the terminal's
stop character. The initial value for the kill character is
taken to be the terminal's stop character.
susp
If telnet is in localchars mode, or
LINEMODE is enabled, and the suspend character is typed, a
TELNET SUSP sequence (see send, susp above) is sent to
the remote host. The initial value for the suspend character is taken
to be the terminal's suspend character.
tracefile
This is the file to which the output, generated when the
netdata or the debug option is TRUE, will be written. If
tracefile is set to "-", then tracing information will
be written to standard output (the default).
worderase
If telnet is operating in LINEMODE or
"old line by line" mode, then this character is taken to be the
terminal's worderase character. The initial value for the
worderase character is taken to be the terminal's worderase
character.
?
Displays the legal set and unset
commands.
slc state
The
slc (Set Local Characters) command is used to
set or change the state of special characters when the
TELNET LINEMODE
option has been enabled. Special characters are characters that get mapped to
TELNET commands sequences (like
ip or
quit) or line
editing characters (like
erase and
kill). By default, the local
special characters are exported. The following values for
state are
valid:
check
Verifies the settings for the current special characters.
The remote side is requested to send all the current special character
settings. If there are any discrepancies with the local side, the local
settings will switch to the remote values.
export
Switches to the local defaults for the special
characters. The local default characters are those of the local terminal at
the time when telnet was started.
import
Switches to the remote defaults for the special
characters. The remote default characters are those of the remote system at
the time when the TELNET connection was established.
?
Prints out help information for the slc
command.
toggle argument...
Toggle between
TRUE and
FALSE the various
flags that control how
telnet responds to events. More than one
argument may be specified. The state of these flags may be interrogated with
the
display command. Valid arguments are:
authdebug
Turns on debugging information for the authentication
code.
autodecrypt
When the 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.
autologin
If the remote side supports the TELNET
AUTHENTICATION option, telnet attempts to use it to perform
automatic authentication. If the AUTHENTICATION option is not
supported, the user's login name is propagated through the TELNET
ENVIRON option. This command is the same as specifying the -a
option on the open command.
autoflush
If
autoflush and
localchars are both
TRUE, then when the
ao,
intr, or
quit characters
are recognized (and transformed into
TELNET sequences; see
set
for details),
telnet refuses to display any data on the user's terminal
until the remote system acknowledges (using a
TELNET Timing Mark
option) that it has processed those
TELNET sequences. The initial value
for this toggle is
TRUE if the terminal user has not done an "stty
noflsh". Otherwise, the value is
FALSE (see
stty(1)).
autosynch
If autosynch and localchars are both
TRUE, then when either the interrupt or quit characters
are typed (see set for descriptions of interrupt and
quit), the resulting TELNET sequence sent is followed by the
TELNET SYNCH sequence. This procedure should cause the remote
system to begin throwing away all previously typed input until both of the
TELNET sequences have been read and acted upon. The initial value of
this toggle is FALSE.
binary
Enable or disable the TELNET BINARY option on both
input and output.
inbinary
Enable or disable the TELNET BINARY option on
input.
outbinary
Enable or disable the TELNET BINARY option on
output.
crlf
Determines how carriage returns are sent. If the value is
TRUE, then carriage returns will be sent as
<CR><LF>. If the value is FALSE, then carriage
returns will be send as <CR><NUL>. The initial value for
this toggle is FALSE.
crmod
Toggle RETURN mode. When this mode is enabled, most
RETURN characters received from the remote host will be mapped into a 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 useful only
for remote hosts that send RETURN but never send LINEFEED. The initial value
for this toggle is FALSE.
debug
Toggle socket level debugging (only available to the
super-user). The initial value for this toggle is FALSE.
encdebug
Turns on debugging information for the encryption
code.
localchars
If this toggle is TRUE, then the flush,
interrupt, quit, erase, and kill characters (see
set) are recognized locally, and transformed into appropriate
TELNET control sequences, respectively ao, ip,
brk, ec, and el (see send). The initial value for
this toggle is TRUE in "line by line" mode, and FALSE
in "character at a time" mode. When the LINEMODE option is
enabled, the value of localchars is ignored, and assumed always to be
TRUE. If LINEMODE has ever been enabled, then quit is
sent as abort, and eof and suspend are sent as eof
and susp (see send above).
netdata
Toggle the display of all network data (in hexadecimal
format). The initial value for this toggle is FALSE.
options
Toggle the display of some internal TELNET
protocol processing (having to do with telnet options). The initial
value for this toggle is FALSE.
prettydump
When the netdata toggle is enabled, if
prettydump is enabled, the output from the netdata command will
be formatted in a more user readable format. Spaces are put between each
character in the output. The beginning of any TELNET escape sequence is
preceded by an asterisk (*) to aid in locating them.
skiprc
When the skiprc toggle is TRUE,
TELNET skips the reading of the .telnetrc file in the user's
home directory when connections are opened. The initial value for this toggle
is FALSE.
termdata
Toggles the display of all terminal data (in hexadecimal
format). The initial value for this toggle is FALSE.
verbose_encrypt
When the verbose_encrypt flag is TRUE,
TELNET prints out a message each time encryption is enabled or
disabled. The initial value for this toggle is FALSE.
?
Display the legal toggle commands.
environ argument...
The
environ command is used to manipulate
variables that may be sent through the
TELNET ENVIRON option. The
initial set of variables is taken from the users environment. Only the
DISPLAY and
PRINTER variables are exported by default. Valid
arguments for the
environ command are:
define variable value
Define variable to have a value of value.
Any variables defined by this command are automatically exported. The
value may be enclosed in single or double quotes, so that tabs and
spaces may be included.
undefine variable
Remove variable from the list of environment
variables.
export variable
Mark the variable to be exported to the remote
side.
unexport variable
Mark the variable to not be exported unless
explicitly requested by the remote side.
list
List the current set of environment variables. Those
marked with an asterisk (*) will be sent automatically. Other variables
will be sent only if explicitly requested.
?
Prints out help information for the environ
command.
logout
Sends the telnet logout option to the remote side.
This command is similar to a close command. However, if the remote side
does not support the logout option, nothing happens. If, however, the
remote side does support the logout option, this command should cause
the remote side to close the TELNET connection. If the remote side also
supports the concept of suspending a user's session for later reattachment,
the logout argument indicates that the remote side should terminate the
session immediately.