protocol
The
command
is used to communicate with another host using the
protocol.
If
is invoked without the
argument, it enters command mode,
indicated by its prompt
In this mode, it accepts and executes the commands listed below.
If it is invoked with arguments, it performs an
command with those arguments.
Options:
Specifies an 8-bit data path. This causes an attempt to
negotiate the
option on both input and output.
Stops any character from being recognized as an escape character.
If Kerberos V5 authentication is being used, the
option allows the local credentials to be forwarded
to the remote system, including any credentials that
have already been forwarded into the local environment.
Specifies no automatic login to the remote system.
Specifies an 8-bit data path on output. This causes the
BINARY option to be negotiated on output.
Sets the IP type-of-service (TOS) option for the telnet
connection to the value
which can be a numeric TOS value
or, on systems that support it, a symbolic
TOS name found in the /etc/iptos file.
Disables the
type of authentication.
Attempt automatic login.
Currently, this sends the user name via the
variable
of the
option if supported by the remote system.
The name used is that of the current user as returned by
if it agrees with the current user ID,
otherwise it is the name associated with the user ID.
Disables the reading of the user's
file. (See the
command on this man page.)
Sets the initial value of the
toggle to
Sets the initial
escape character to
If
is omitted, then
there will be no escape character.
If Kerberos V5 authentication is being used, the
option allows the local credentials to be forwarded to the remote system.
If Kerberos authentication is being used, the
option requests that telnet obtain tickets for the remote host in
realm realm instead of the remote host's realm, as determined
by
When connecting to the remote system, if the remote system
understands the
option, then
will be sent to the remote system as the value for the variable USER.
This option implies the
option.
This option may also be used with the
command.
Opens
for recording trace information.
See the
command below.
Specifies a user interface similar to
In this
mode, the escape character is set to the tilde (~) character,
unless modified by the -e option.
Turns on encryption of the data stream if possible. This
option is not available outside of the United States and
Canada.
Indicates the official name, an alias, or the Internet address
of a remote host.
Indicates a port number (address of an application). If a number is
not specified, the default
port is used.
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.
Once a connection has been opened,
will attempt to enable the
option.
If this fails, then
will revert to one of two input modes:
either [Lq]character at a time[Rq]
or [Lq]old line by line[Rq]
depending on what the remote system supports.
When
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.
In [Lq]character at a time[Rq] mode, most
text typed is immediately sent to the remote host for processing.
In [Lq]old line by line[Rq] mode, all text is echoed locally,
and (normally) only completed lines are sent to the remote host.
The [Lq]local 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).
If the
option is enabled, or if the
toggle is
(the default for [Lq]old line by line[Lq]; see below),
the user's
and
characters are trapped locally, and sent as
protocol sequences to the remote side.
If
has ever been enabled, then the user's
and
are also sent as
protocol sequences,
and
is sent as a
instead of
There are options (see
and
below)
which cause this action to flush subsequent output to the terminal
(until the remote host acknowledges the
sequence) and flush previous terminal input
(in the case of
and
While connected to a remote host,
command mode may be entered by typing the
[Lq]escape character[Rq] (initially [Lq]^][Rq]).
When in command mode, the normal terminal editing conventions are available.
The following
commands are available.
Only enough of each command to uniquely identify it need be typed
(this is also true for arguments to the
and
commands).
The auth command manipulates the information sent through the
option. Valid arguments for the
auth command are as follows:
Disables the specified type of authentication. To
obtain a list of available types, use the
command.
Enables the specified type of authentication. To
obtain a list of available types, use the
command.
Lists the current status of the various types of
authentication.
Close a
session and return to command mode.
Displays all, or some, of the
and
values (see below).
The encrypt command manipulates the information sent through the
option.
Note: Because of export controls, the
option is not supported outside of the United States and Canada.
Valid arguments for the encrypt command are as follows:
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
command.
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
command.
This is the same as the
command.
This is the same as the
command.
This is the same as the
command.
This is the same as the
command.
Attempts to start encryption. If you omit
and
both input and output are enabled. To
obtain a list of available types, use the
command.
Lists the current status of encryption.
Stops encryption. If you omit input and output,
encryption is on both input and output.
Sets the default type of encryption to be used
with later
or
commands.
The
command is used to manipulate the
the variables that my be sent through the
option.
The initial set of variables is taken from the users
environment, with only the
and
variables being exported by default.
The
variable is also exported if the
or
options are used.
Valid arguments for the
command are:
Define the variable
to have a value of
Any variables defined by this command are automatically exported.
The
may be enclosed in single or double quotes so
that tabs and spaces may be included.
Remove
from the list of environment variables.
Mark the variable
to be exported to the remote side.
Mark the variable
to not be exported unless
explicitly asked for by the remote side.
List the current set of environment variables.
Those marked with a
will be sent automatically,
other variables will only be sent if explicitly requested.
Prints out help information for the
command.
Sends the
option to the remote side.
This command is similar to a
command; however, if the remote side does not support the
option, nothing happens.
If, however, the remote side does support the
option, this command should cause the remote side to close the
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.
is one of several options, depending on the state of the
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.
Disable the
option, or, if the remote side does not understand the
option, then enter [Lq]character at a time[Lq] mode.
Enable the
option, or, if the remote side does not understand the
option, then attempt to enter [Lq]old-line-by-line[Lq] mode.
Attempt to enable (disable) the
mode of the
option.
This requires that the
option be enabled.
Attempt to enable (disable) the
mode of the
option.
This requires that the
option be enabled.
Attempt to enable (disable) the
mode of the
option.
This requires that the
option be enabled.
Attempt to enable (disable) the
mode of the
option.
This requires that the
option be enabled.
Prints out help information for the
command.
Open a connection to the named host.
If no port number
is specified,
will attempt to contact a
server at the default port.
The host specification may be either a host name (see
or an Internet address specified in the [Lq]dot notation[Rq] (see
The
option may be used to specify the user name
to be passed to the remote system via the
option.
When connecting to a non-standard port,
omits any automatic initiation of
options. When the port number is preceded by a minus sign,
the initial option negotiation is done.
After establishing a connection, the file
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
commands and are processed as if they had been typed
in manually to the
command prompt.
Close any open
session and exit
An end of file (in command mode) will also close a session and exit.
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):
Sends the
(Abort
processes)
sequence.
Sends the
(Abort Output) sequence, which should cause the remote system to flush
all output
the remote system
the user's terminal.
Sends the
(Are You There)
sequence, to which the remote system may or may not choose to respond.
Sends the
(Break) sequence, which may have significance to the remote
system.
Sends the
(Erase Character)
sequence, which should cause the remote system to erase the last character
entered.
Sends the
(Erase Line)
sequence, which should cause the remote system to erase the line currently
being entered.
Sends the
(End Of File)
sequence.
Sends the
(End of Record)
sequence.
Sends the current
escape character (initially [Lq]^[Rq]).
Sends the
(Go Ahead)
sequence, which likely has no significance to the remote system.
If the remote side supports the
command,
will send the subnegotiation to request that the server send
its current option status.
Sends the
(Interrupt Process) sequence, which should cause the remote
system to abort the currently running process.
Sends the
(No OPeration)
sequence.
Sends the
(SUSPend process)
sequence.
Sends the
sequence.
This sequence causes the remote system to discard all previously typed
(but not yet read) input.
This sequence is sent as
urgent
data (and may not work if the remote system is a
system -- if
it doesn't work, a lower case [Lq]r[Rq] may be echoed on the terminal).
Sends the
sequence.
can be either a decimal number between 0 and 255,
or a symbolic name for a specific
command.
can also be either
or
to print out help information, including
a list of known symbolic names.
Prints out help information for the
command.
The
command will set any one of a number of
variables to a specific value or to
The special value
turns off the function associated with
the variable, this is equivalent to using the
command.
The
command will disable or set to
any of the specified functions.
The values of variables may be interrogated with the
command.
The variables which may be set or unset, but not toggled, are
listed here. In addition, any of the variables for the
command may be explicitly set or unset using
the
and
commands.
If
is in localchars mode, or
is enabled, and the status character is typed, a
sequence (see
preceding) is sent to the
remote host. The initial value for the "Are You There"
character is the terminal's status character.
This is the value (initially [Lq]^E[Rq]) which, when in
[Lq]line 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).
If
is operating in
or [Lq]old 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
character.
If
is in
mode (see
below),
if
is operating in [Lq]character at a time[Rq] mode, then when this
character is typed, a
sequence (see
above)
is sent to the remote system.
The initial value for the erase character is taken to be
the terminal's
character.
This is the
escape character (initially [Lq]^[[Rq]) which causes entry
into
command mode (when connected to a remote system).
If
is in
mode (see
below)
and the
character is typed, a
sequence (see
above)
is sent to the remote host.
The initial value for the flush character is taken to be
the terminal's
character.
If
is operating in
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.
If
is in
mode (see
below)
and the
character is typed, a
sequence (see
above)
is sent to the remote host.
The initial value for the interrupt character is taken to be
the terminal's
character.
If
is in
mode (see
below),
if
is operating in [Lq]character at a time[Rq] mode, then when this
character is typed, a
sequence (see
above)
is sent to the remote system.
The initial value for the kill character is taken to be
the terminal's
character.
If
is operating in
or [Lq]old line by line[Lq] mode, then this character is taken to
be the terminal's
character.
The initial value for the lnext character is taken to be
the terminal's
character.
If
is in
mode (see
below)
and the
character is typed, a
sequence (see
above)
is sent to the remote host.
The initial value for the quit character is taken to be
the terminal's
character.
If
is operating in
or [Lq]old line by line[Lq] mode, then this character is taken to
be the terminal's
character.
The initial value for the reprint character is taken to be
the terminal's
character.
This is the rlogin escape character.
If set, the normal
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.
If the
option has been enabled,
then this character is taken to
be the terminal's
character.
The initial value for the kill character is taken to be
the terminal's
character.
If the
option has been enabled,
then this character is taken to
be the terminal's
character.
The initial value for the kill character is taken to be
the terminal's
character.
If
is in
mode, or
is enabled, and the
character is typed, a
sequence (see
above)
is sent to the remote host.
The initial value for the suspend character is taken to be
the terminal's
character.
This is the file to which the output, caused by
or
tracing being
will be written. If it is set to
then tracing information will be written to standard output (the default).
If
is operating in
or [Lq]old line by line[Lq] mode, then this character is taken to
be the terminal's
character.
The initial value for the worderase character is taken to be
the terminal's
character.
Displays the legal
commands.
The
command (Set Local Characters) is used to set
or change the state of the the special
characters when the
option has
been enabled. Special characters are characters that get
mapped to
commands sequences (like
or
or line editing characters (like
and
By default, the local special characters are exported.
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.
Switch to the local defaults for the special characters. The
local default characters are those of the local terminal at
the time when
was started.
Switch to the remote defaults for the special characters.
The remote default characters are those of the remote system
at the time when the
connection was established.
Prints out help information for the
command.
Show the current status of
This includes the peer one is connected to, as well
as the current mode.
Toggle (between
and
various flags that control how
responds to events.
These flags may be set explicitly to
or
using the
and
commands listed above.
More than one argument may be specified.
The state of these flags may be interrogated with the
command.
Valid arguments are:
Turns on debugging information for the authentication code.
If
and
are both
then when the
or
characters are recognized (and transformed into
sequences; see
above for details),
refuses to display any data on the user's terminal
until the remote system acknowledges (via a
option)
that it has processed those
sequences.
The initial value for this toggle is
if the terminal user had not
done an "stty noflsh", otherwise
(see
When the
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.
Note: Because of export controls, the
option is not supported outside the United States and Canada.
If the remote side supports the
option
attempts to use it to perform automatic authentication. If the
option is not supported, the user's login
name are propagated through the
option.
This command is the same as specifying
option on the
command.
If
and
are both
then when either the
or
characters is typed (see
above for descriptions of the
and
characters), the resulting
sequence sent is followed by the
sequence.
This procedure
cause the remote system to begin throwing away all previously
typed input until both of the
sequences have been read and acted upon.
The initial value of this toggle is
Enable or disable the
option on both input and output.
Enable or disable the
option on input.
Enable or disable the
option on output.
If this is
then carriage returns will be sent as
If this is
then carriage returns will be send as
The initial value for this toggle is
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
Toggles socket level debugging (useful only to the
The initial value for this toggle is
Turns on debugging information for the encryption code.
If this is
then the
and
characters (see
above) are recognized locally, and transformed into (hopefully) appropriate
control sequences
(respectively
and
see
above).
The initial value for this toggle is
in [Lq]old line by line[Rq] mode,
and
in [Lq]character at a time[Rq] mode.
When the
option is enabled, the value of
is ignored, and assumed to always be
If
has ever been enabled, then
is sent as
and
suspend
are sent as
see
above).
Toggles the display of all network data (in hexadecimal format).
The initial value for this toggle is
Toggles the display of some internal
protocol processing (having to do with
options).
The initial value for this toggle is
When the
toggle is enabled, if
is enabled the output from the
command will be formatted in a more user readable format.
Spaces are put between each character in the output, and the
beginning of any
escape sequence is preceded by a '*' to aid in locating them.
When the skiprc toggle is
skips the reading of the
file in the users home
directory when connections are opened. The initial
value for this toggle is
Toggles the display of all terminal data (in hexadecimal format).
The initial value for this toggle is
When the
toggle is
prints out a message each time encryption is enabled or
disabled. The initial value for this toggle is
Note: Because of export controls, data encryption
is not supported outside of the United States and Canada.
Displays the legal
commands.
Suspend
This command only works when the user is using the
Execute a single command in a subshell on the local
system. If
is omitted, then an interactive
subshell is invoked.
Get help. With no arguments,
prints a help summary.
If a command is specified,
will print the help information for just that command.
uses at least the
and
environment variables.
Other environment variables may be propagated
to the other side via the
option.
user customized telnet startup values
The
command appeared in
On some remote systems, echo has to be turned off manually when in
[Lq]old line by line[Rq] mode.
In [Lq]old line by line[Rq] mode or
the terminal's
character is only recognized (and sent to the remote system)
when it is the first character on a line.