solaris - telnet (1)
NAME
telnet - user interface to a remote system using the TELNET
protocol
SYNOPSIS
telnet [ -8ELcdr ] [ -e escape_char ] [ -l user ] [ -n file
] [ host [ port ] ]
AVAILABILITY
SUNWcsu
DESCRIPTION
telnet communicates with another host using the TELNET pro-
tocol. If telnet is invoked without arguments, it enters
command mode, indicated by its prompt telnet>>. In this
mode, it accepts and executes its associated commands. (See
"TELNET Commands" below.) If it is invoked with arguments,
it performs an open command with those arguments.
Once a connection has been opened, telnet enters input mode.
In this mode, text typed is sent to the remote host. The
input mode entered will be either "line mode," "character at
a time," or "old line by line," depending on what the remote
system supports.
In line mode, character processing is done on the local sys-
tem, 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.
In character at a time mode, most text typed is immediately
sent to the remote host for processing.
In old line by line mode, all text is echoed locally, and
(normally) only completed lines are sent to the remote host.
The "local echo character" (initially ^E) may be used to
turn off and on the local echo. (Use this mostly to enter
passwords without the password being echoed.).
If the "line mode" option is enabled, or if the localchars
toggle is TRUE (the default in "old line by line" mode), the
user's quit, intr, and flush characters are trapped locally,
and sent as TELNET protocol sequences to the remote side.
If "line mode" has ever been enabled, then the user's susp
and eof are also sent as TELNET protocol sequences. quit is
then sent as a TELNET ABORT instead of BREAK. The options
toggle autoflush, and toggle autosynch cause this action to
flush subsequent output to the terminal (until the remote
host acknowledges the TELNET sequence) and flush previous
terminal input, in the case of quit and intr.
While connected to a remote host, the user can enter telnet
command mode by typing the telnet escape character (ini-
tially ^]). When in command mode, the normal terminal edit-
ing conventions are available.
OPTIONS
-8 Specifies an 8-bit data path. Negotiating the TELNET
BINARY option is attempted for both input and output.
-E Stops any character from being recognized as an escape
character.
-L Specifies an 8-bit data path on output. This causes
the BINARY option to be negotiated on output.
-c Disables the reading of the user's telnetrc file.
(See the toggle skiprc command on this man page.)
-d Sets the initial value of the debug toggle to true.
-e escape_char
Sets the initial escape character to escape_char.
Escape_char may also be a two character sequence con-
sisting of '^' followed by one character. If the
second character is '?', the DEL character is selected.
Otherwise the second character is converted to a con-
trol character and used as the escape character. If
the escape character is the null string, (i.e. -e ''),
it is disabled.
-l user
When connecting to a remote system that understands the
ENVIRON option, then user will be sent to the remote
system as the value for the variable USER.
-n tracefile
Opens tracefile for recording trace information. See
the set tracefile command below.
-r Specifies a user interface similar to rlogin. In this
mode, the escape character is set to the tilde (~)
character, unless modified by the -e option. The rlo-
gin escape character is only recognized when it is pre-
ceded by a carriage return. In this mode, the telnet
escape character, normally '^]', must still precede a
telnet command. The rlogin escape character can also
be followed by '.\r' or '^Z', and, like rlogin(1),
closes or suspends the connection, respectively. This
option is an uncommitted interface and may change in
the future.
USAGE
telnet Commands
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 com-
mands.)
open [ -l user ] 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(4)) or an Internet
address specified in the "dot notation" (see inet(7P)).
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.
quit Same as close, above.
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.
Type is one of:
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, arguments).
? [ command ]
Get help. With no arguments, telnet prints a help sum-
mary. If a command is specified, telnet will print the
help information for just that command.
sendarguments
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 (ini-
tially ^]).
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
lower case 'r' may be echoed on the terminal.
brk 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 sys-
tem.
getstatus
If the remote side supports the TELNET STATUS com-
mand, 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 indi-
cated. Option may be the text name of the proto-
col 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 speci-
fied 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
^]), which enters telnet command mode when con-
nected to a remote system.
interrupt
If telnet is in localchars mode (see toggle local-
chars) 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 inter-
rupt character is taken to be the terminal's intr
character.
quit If telnet is in localchars mode and the quit char-
acter 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 flushout-
put 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 ini-
tial 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 ini-
tial 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 sys-
tem. 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 TEL-
NET 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
comes 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 ini-
tial 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 dis-
able 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, caused by
the netdata or the debug option being TRUE, will
be written. If it 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 char-
acters are characters that get mapped to TELNET com-
mands sequences (like ip or quit ) or line editing
characters (like erase and kill). By default, the
local special characters are exported.
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 tel-
net 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 arguments...
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:
autoflush
If autoflush and localchars are both TRUE, then
when the ao, intr, or quit characters are recog-
nized (and transformed into TELNET sequences; see
set for details), telnet refuses to display any
data on the user's terminal until the remote sys-
tem 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 fol-
lowed by the TELNET SYNCH sequence. This pro-
cedure 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 out-
put.
crlf Determines how carriage returns are sent. If the
value is TRUE, then carriage returns will be sent
as <CR><LF>. If this 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 char-
acters 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 superuser). The initial value for this toggle
is FALSE.
localchars
If this toggle is TRUE, then the flush, interrupt,
quit, erase, and kill characters (see set) are
recognized locally, and transformed into appropri-
ate 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 local-
chars is ignored, and assumed to always 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 hexade-
cimal format). The initial value for this toggle
is FALSE.
options
Toggle the display of some internal TELNET proto-
col 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 out-
put. 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 ini-
tial value for this toggle is FALSE.
termdata
Toggles the display of all terminal data (in hexa-
decimal format). The initial value for this tog-
gle is FALSE.
? Display the legal toggle commands.
environ arguments...
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 automati-
cally exported. The value may be enclosed in sin-
gle or double quotes, so that tabs and spaces may
be included.
undefine variable
Remove variable from the list of environment vari-
ables. export variable
export
variable Mark the variable to be exported to the
remote side.
unexport variable
Mark the variable to not be exported unless expli-
citly 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 com-
mand.
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 argu-
ment indicates that the remote side should terminate
the session immediately.
FILES
$HOME/.telnetrc
SEE ALSO
rlogin(1), sh(1), stty(1), hosts(4), inet(7P)
NOTES
On some remote systems, echo has to be turned off manually
when in "line by line" mode.
In "old line by line" mode, or LINEMODE the terminal's EOF
character is only recognized (and sent to the remote system)
when it is the first character on a line.