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32 .\" @(#)telnet.1 8.6 (Berkeley) 6/1/94
40 .Nd user interface to the
48 .Op Fl e Ar escapechar
61 is used to communicate with another host using the
66 is invoked without the
68 argument, it enters command mode,
69 indicated by its prompt
71 In this mode, it accepts and executes the commands listed below.
72 If it is invoked with arguments, it performs an
74 command with those arguments.
77 .Bl -tag -width indent
81 to use IPv4 addresses only.
85 to use IPv6 addresses only.
87 Specifies an 8-bit data path. This causes an attempt to
90 option on both input and output.
92 Stops any character from being recognized as an escape character.
94 If Kerberos V5 authentication is being used, the
96 option allows the local credentials to be forwarded
97 to the remote system, including any credentials that
98 have already been forwarded into the local environment.
100 Specifies no automatic login to the remote system.
102 Specifies an 8-bit data path on output. This causes the
104 option to be negotiated on output.
106 Prevents IP address to name lookup when destination host is given
109 Sets the IP type-of-service (TOS) option for the telnet
110 connection to the value
112 which can be a numeric TOS value
113 or, on systems that support it, a symbolic
114 TOS name found in the
120 type of authentication.
122 Attempt automatic login.
123 This is now the default, so this option is ignored.
124 Currently, this sends the user name via the
129 option if supported by the remote system.
130 The name used is that of the current user as returned by
132 if it agrees with the current user ID,
133 otherwise it is the name associated with the user ID.
135 Disables the reading of the user's
139 command on this man page.)
141 Sets the initial value of the
145 .It Fl e Ar escapechar
153 there will be no escape character.
155 If Kerberos V5 authentication is being used, the
157 option allows the local credentials to be forwarded to the remote system.
159 If Kerberos authentication is being used, the
163 obtain tickets for the remote host in
166 instead of the remote host's realm, as determined by
167 .Xr krb_realmofhost 3 .
169 When connecting to the remote system, if the remote system
174 will be sent to the remote system as the value for the variable
176 This option implies the
179 This option may also be used with the
182 .It Fl n Ar tracefile
185 for recording trace information.
190 Specifies a user interface similar to
193 mode, the escape character is set to the tilde (~) character,
194 unless modified by the
198 Set the source IP address for the
202 which can be an IP address or a host name.
208 addresses only (e.g.,
210 domain sockets, accessed with a file path).
212 Turns on encryption of the data stream if possible.
213 This is now the default, so this option is ignored.
215 Suppresses encryption of the data stream.
217 Indicates the official name, an alias, or the Internet address
224 establishes a connection to the corresponding named socket.
226 Indicates a port number (address of an application). If a number is
227 not specified, the default
232 When in rlogin mode, a line of the form ~. disconnects from the
233 remote host; ~ is the
236 Similarly, the line ~^Z suspends the
239 The line ~^] escapes to the normal
243 Once a connection has been opened,
245 will attempt to enable the
250 will revert to one of two input modes:
251 either \*(Lqcharacter at a time\*(Rq
252 or \*(Lqold line by line\*(Rq
253 depending on what the remote system supports.
257 is enabled, character processing is done on the
258 local system, under the control of the remote system. When input
259 editing or character echoing is to be disabled, the remote system
260 will relay that information. The remote system will also relay
261 changes to any special characters that happen on the remote
262 system, so that they can take effect on the local system.
264 In \*(Lqcharacter at a time\*(Rq mode, most
265 text typed is immediately sent to the remote host for processing.
267 In \*(Lqold line by line\*(Rq mode, all text is echoed locally,
268 and (normally) only completed lines are sent to the remote host.
269 The \*(Lqlocal echo character\*(Rq (initially \*(Lq^E\*(Rq) may be used
270 to turn off and on the local echo
271 (this would mostly be used to enter passwords
272 without the password being echoed).
276 option is enabled, or if the
280 (the default for \*(Lqold line by line\*(Rq; see below),
286 characters are trapped locally, and sent as
288 protocol sequences to the remote side.
291 has ever been enabled, then the user's
304 There are options (see
311 which cause this action to flush subsequent output to the terminal
312 (until the remote host acknowledges the
314 sequence) and flush previous terminal input
320 While connected to a remote host,
322 command mode may be entered by typing the
324 \*(Lqescape character\*(Rq (initially \*(Lq^]\*(Rq).
325 When in command mode, the normal terminal editing conventions are available.
329 commands are available.
330 Only enough of each command to uniquely identify it need be typed
331 (this is also true for arguments to the
342 .Bl -tag -width "mode type"
343 .It Ic auth Ar argument ...
344 The auth command manipulates the information sent through the
345 .Dv TELNET AUTHENTICATE
346 option. Valid arguments for the
349 .Bl -tag -width "disable type"
350 .It Ic disable Ar type
351 Disables the specified type of authentication. To
352 obtain a list of available types, use the
355 .It Ic enable Ar type
356 Enables the specified type of authentication. To
357 obtain a list of available types, use the
361 Lists the current status of the various types of
367 session and return to command mode.
368 .It Ic display Ar argument ...
369 Displays all, or some, of the
374 .It Ic encrypt Ar argument ...
375 The encrypt command manipulates the information sent through the
379 Note: Because of export controls, the
381 option is not supported outside of the United States and Canada.
383 Valid arguments for the
387 .It Ic disable Ar type Xo
388 .Op Cm input | output
390 Disables the specified type of encryption. If you
391 omit the input and output, both input and output
392 are disabled. To obtain a list of available
394 .Ic encrypt disable ?\&
396 .It Ic enable Ar type Xo
397 .Op Cm input | output
399 Enables the specified type of encryption. If you
400 omit input and output, both input and output are
401 enabled. To obtain a list of available types, use the
402 .Ic encrypt enable ?\&
405 This is the same as the
406 .Ic encrypt start input
409 This is the same as the
410 .Ic encrypt stop input
413 This is the same as the
414 .Ic encrypt start output
417 This is the same as the
418 .Ic encrypt stop output
420 .It Ic start Op Cm input | output
421 Attempts to start encryption. If you omit
425 both input and output are enabled. To
426 obtain a list of available types, use the
427 .Ic encrypt enable ?\&
430 Lists the current status of encryption.
431 .It Ic stop Op Cm input | output
432 Stops encryption. If you omit input and output,
433 encryption is on both input and output.
435 Sets the default type of encryption to be used
442 .It Ic environ Ar arguments ...
445 command is used to manipulate the
446 variables that may be sent through the
449 The initial set of variables is taken from the users
450 environment, with only the
454 variables being exported by default.
457 variable is also exported if the
463 Valid arguments for the
467 .It Ic define Ar variable value
472 Any variables defined by this command are automatically exported.
475 may be enclosed in single or double quotes so
476 that tabs and spaces may be included.
477 .It Ic undefine Ar variable
480 from the list of environment variables.
481 .It Ic export Ar variable
484 to be exported to the remote side.
485 .It Ic unexport Ar variable
488 to not be exported unless
489 explicitly asked for by the remote side.
491 List the current set of environment variables.
494 will be sent automatically,
495 other variables will only be sent if explicitly requested.
497 Prints out help information for the
504 option to the remote side.
505 This command is similar to a
507 command; however, if the remote side does not support the
509 option, nothing happens.
510 If, however, the remote side does support the
512 option, this command should cause the remote side to close the
515 If the remote side also supports the concept of
516 suspending a user's session for later reattachment,
517 the logout argument indicates that you
518 should terminate the session immediately.
521 is one of several options, depending on the state of the
524 The remote host is asked for permission to go into the requested mode.
525 If the remote host is capable of entering that mode, the requested
526 mode will be entered.
531 option, or, if the remote side does not understand the
533 option, then enter \*(Lqcharacter at a time\*(Rq mode.
537 option, or, if the remote side does not understand the
539 option, then attempt to enter \*(Lqold-line-by-line\*(Rq mode.
540 .It Ic isig Pq Ic \-isig
541 Attempt to enable (disable) the
546 This requires that the
549 .It Ic edit Pq Ic \-edit
550 Attempt to enable (disable) the
555 This requires that the
558 .It Ic softtabs Pq Ic \-softtabs
559 Attempt to enable (disable) the
564 This requires that the
567 .It Ic litecho Pq Ic \-litecho
568 Attempt to enable (disable) the
573 This requires that the
577 Prints out help information for the
584 .Op Oo Fl Oc Ns Ar port
586 Open a connection to the named host.
590 will attempt to contact a
592 server at the default port.
593 The host specification may be either a host name (see
595 an Internet address specified in the \*(Lqdot notation\*(Rq (see
597 or IPv6 host name or IPv6 coloned-hexadecimal addreess.
600 option may be used to specify the user name
601 to be passed to the remote system via the
604 When connecting to a non-standard port,
606 omits any automatic initiation of
608 options. When the port number is preceded by a minus sign,
609 the initial option negotiation is done.
610 After establishing a connection, the file
613 users home directory is opened. Lines beginning with a # are
614 comment lines. Blank lines are ignored. Lines that begin
615 without white space are the start of a machine entry. The
616 first thing on the line is the name of the machine that is
617 being connected to. The rest of the line, and successive
618 lines that begin with white space are assumed to be
620 commands and are processed as if they had been typed
629 An end of file (in command mode) will also close a session and exit.
630 .It Ic send Ar arguments
631 Sends one or more special character sequences to the remote host.
632 The following are the arguments which may be specified
633 (more than one argument may be specified at a time):
635 .Bl -tag -width escape
645 (Abort Output) sequence, which should cause the remote system to flush
655 sequence, to which the remote system may or may not choose to respond.
659 (Break) sequence, which may have significance to the remote
665 sequence, which should cause the remote system to erase the last character
671 sequence, which should cause the remote system to erase the line currently
686 escape character (initially \*(Lq^\*(Rq).
691 sequence, which likely has no significance to the remote system.
693 If the remote side supports the
697 will send the subnegotiation to request that the server send
698 its current option status.
702 (Interrupt Process) sequence, which should cause the remote
703 system to abort the currently running process.
718 This sequence causes the remote system to discard all previously typed
719 (but not yet read) input.
720 This sequence is sent as
723 data (and may not work if the remote system is a
726 it doesn't work, a lower case \*(Lqr\*(Rq may be echoed on the terminal).
736 can be either a decimal number between 0 and 255,
737 or a symbolic name for a specific
745 to print out help information, including
746 a list of known symbolic names.
748 Prints out help information for the
752 .It Ic set Ar argument value
753 .It Ic unset Ar argument value
756 command will set any one of a number of
758 variables to a specific value or to
762 turns off the function associated with
763 the variable, this is equivalent to using the
768 command will disable or set to
770 any of the specified functions.
771 The values of variables may be interrogated with the
774 The variables which may be set or unset, but not toggled, are
775 listed here. In addition, any of the variables for the
777 command may be explicitly set or unset using
783 .Bl -tag -width escape
787 is in localchars mode, or
789 is enabled, and the status character is typed, a
793 preceding) is sent to the
794 remote host. The initial value for the \*(LqAre You There\*(Rq
795 character is the terminal's status character.
797 This is the value (initially \*(Lq^E\*(Rq) which, when in
798 \*(Lqline by line\*(Rq mode, toggles between doing local echoing
799 of entered characters (for normal processing), and suppressing
800 echoing of entered characters (for entering, say, a password).
806 or \*(Lqold line by line\*(Rq mode, entering this character
807 as the first character on a line will cause this character to be
808 sent to the remote system.
809 The initial value of the eof character is taken to be the terminal's
824 is operating in \*(Lqcharacter at a time\*(Rq mode, then when this
825 character is typed, a
831 is sent to the remote system.
832 The initial value for the erase character is taken to be
839 escape character (initially \*(Lq^[\*(Rq) which causes entry
842 command mode (when connected to a remote system).
854 character is typed, a
860 is sent to the remote host.
861 The initial value for the flush character is taken to be
872 characters that, when typed, cause partial lines to be
873 forwarded to the remote system. The initial value for
874 the forwarding characters are taken from the terminal's
875 eol and eol2 characters.
887 character is typed, a
893 is sent to the remote host.
894 The initial value for the interrupt character is taken to be
910 is operating in \*(Lqcharacter at a time\*(Rq mode, then when this
911 character is typed, a
917 is sent to the remote system.
918 The initial value for the kill character is taken to be
927 or \*(Lqold line by line\*(Rq mode, then this character is taken to
931 The initial value for the lnext character is taken to be
946 character is typed, a
952 is sent to the remote host.
953 The initial value for the quit character is taken to be
962 or \*(Lqold line by line\*(Rq mode, then this character is taken to
966 The initial value for the reprint character is taken to be
971 This is the rlogin escape character.
974 escape character is ignored unless it is
975 preceded by this character at the beginning of a line.
976 This character, at the beginning of a line followed by
977 a "." closes the connection; when followed by a ^Z it
980 command. The initial state is to
986 .Dv TELNET TOGGLE-FLOW-CONTROL
987 option has been enabled,
988 then this character is taken to
992 The initial value for the start character is taken to be
998 .Dv TELNET TOGGLE-FLOW-CONTROL
999 option has been enabled,
1000 then this character is taken to
1004 The initial value for the stop character is taken to be
1017 character is typed, a
1023 is sent to the remote host.
1024 The initial value for the suspend character is taken to be
1029 This is the file to which the output, caused by
1035 will be written. If it is set to
1037 then tracing information will be written to standard output (the default).
1043 or \*(Lqold line by line\*(Rq mode, then this character is taken to
1047 The initial value for the worderase character is taken to be
1057 .It Ic skey Ar sequence challenge
1060 command computes a response to the S/Key challenge.
1064 command (Set Local Characters) is used to set
1065 or change the state of the special
1069 been enabled. Special characters are characters that get
1072 commands sequences (like
1076 or line editing characters (like
1080 By default, the local special characters are exported.
1083 Verify the current settings for the current special characters.
1084 The remote side is requested to send all the current special
1085 character settings, and if there are any discrepancies with
1086 the local side, the local side will switch to the remote value.
1088 Switch to the local defaults for the special characters. The
1089 local default characters are those of the local terminal at
1094 Switch to the remote defaults for the special characters.
1095 The remote default characters are those of the remote system
1096 at the time when the
1098 connection was established.
1100 Prints out help information for the
1105 Show the current status of
1107 This includes the peer one is connected to, as well
1108 as the current mode.
1109 .It Ic toggle Ar arguments ...
1114 various flags that control how
1117 These flags may be set explicitly to
1125 commands listed above.
1126 More than one argument may be specified.
1127 The state of these flags may be interrogated with the
1130 Valid arguments are:
1133 Turns on debugging information for the authentication code.
1145 characters are recognized (and transformed into
1151 refuses to display any data on the user's terminal
1152 until the remote system acknowledges (via a
1153 .Dv TELNET TIMING MARK
1155 that it has processed those
1158 The initial value for this toggle is
1160 if the terminal user had not
1161 done an "stty noflsh", otherwise
1168 option is negotiated, by
1169 default the actual encryption (decryption) of the data
1170 stream does not start automatically. The autoencrypt
1171 (autodecrypt) command states that encryption of the
1172 output (input) stream should be enabled as soon as
1175 Note: Because of export controls, the
1177 option is not supported outside the United States and Canada.
1179 If the remote side supports the
1180 .Dv TELNET AUTHENTICATION
1183 attempts to use it to perform automatic authentication. If the
1185 option is not supported, the user's login
1186 name are propagated through the
1189 This command is the same as specifying
1201 then when either the
1205 characters is typed (see
1207 above for descriptions of the
1211 characters), the resulting
1213 sequence sent is followed by the
1218 cause the remote system to begin throwing away all previously
1219 typed input until both of the
1221 sequences have been read and acted upon.
1222 The initial value of this toggle is
1225 Enable or disable the
1227 option on both input and output.
1229 Enable or disable the
1233 Enable or disable the
1239 then carriage returns will be sent as
1243 then carriage returns will be send as
1245 The initial value for this toggle is
1248 Toggle carriage return mode.
1249 When this mode is enabled, most carriage return characters received from
1250 the remote host will be mapped into a carriage return followed by
1252 This mode does not affect those characters typed by the user, only
1253 those received from the remote host.
1254 This mode is not very useful unless the remote host
1255 only sends carriage return, but never line feed.
1256 The initial value for this toggle is
1259 Toggles socket level debugging (useful only to the
1261 The initial value for this toggle is
1264 Turns on debugging information for the encryption code.
1277 above) are recognized locally, and transformed into (hopefully) appropriate
1290 The initial value for this toggle is
1292 in \*(Lqold line by line\*(Rq mode,
1295 in \*(Lqcharacter at a time\*(Rq mode.
1298 option is enabled, the value of
1300 is ignored, and assumed to always be
1304 has ever been enabled, then
1320 Toggles the display of all network data (in hexadecimal format).
1321 The initial value for this toggle is
1324 Toggles the display of some internal
1326 protocol processing (having to do with
1329 The initial value for this toggle is
1334 toggle is enabled, if
1336 is enabled the output from the
1338 command will be formatted in a more user readable format.
1339 Spaces are put between each character in the output, and the
1342 escape sequence is preceded by a '*' to aid in locating them.
1344 When the skiprc toggle is
1347 skips the reading of the
1349 file in the users home
1350 directory when connections are opened. The initial
1351 value for this toggle is
1354 Toggles the display of all terminal data (in hexadecimal format).
1355 The initial value for this toggle is
1357 .It Ic verbose_encrypt
1363 prints out a message each time encryption is enabled or
1364 disabled. The initial value for this toggle is
1366 Note: Because of export controls, data encryption
1367 is not supported outside of the United States and Canada.
1376 This command only works when the user is using the
1378 .It Ic \&! Op Ar command
1379 Execute a single command in a subshell on the local
1382 is omitted, then an interactive
1383 subshell is invoked.
1384 .It Ic ?\& Op Ar command
1385 Get help. With no arguments,
1387 prints a help summary.
1392 will print the help information for just that command.
1402 environment variables.
1403 Other environment variables may be propagated
1404 to the other side via the
1414 .Bl -tag -width ~/.telnetrc -compact
1416 user customized telnet startup values
1424 IPv6 support was added by WIDE/KAME project.
1427 On some remote systems, echo has to be turned off manually when in
1428 \*(Lqold line by line\*(Rq mode.
1430 In \*(Lqold line by line\*(Rq mode or
1434 character is only recognized (and sent to the remote system)
1435 when it is the first character on a line.