1telnet(1) User Commands telnet(1)
2
6 telnet - user interface to a remote system using the TELNET protocol
7
9 telnet [-8EFKLacdfrx] [-X atype] [-e escape_char]
10 [-k realm] [-l user] [-n file]
11 [ [ [!] @hop1 [@hop2...] @] host [port]]
12
15 The telnet utility communicates with another host using the TELNET pro‐
16 tocol. If telnet is invoked without arguments, it enters command mode,
17 indicated by its prompt, telnet>. In this mode, it accepts and executes
18 its associated commands. See USAGE. If it is invoked with arguments, it
19 performs an open command with those arguments.
20 If, for example, a host is specified as @hop1@hop2@host, the connection
23 goes through hosts hop1 and hop2, using loose source routing to end at
24 host. If a leading ! is used, the connection follows strict source
25 routing. Notice that when telnet uses IPv6, it can only use loose
26 source routing, and the connection ignores the !.
27 Once a connection has been opened, telnet enters input mode. In this
30 mode, text typed is sent to the remote host. The input mode entered
31 will be either "line mode", "character at a time", or "old line by
32 line", depending upon what the remote system supports.
33 In "line mode", character processing is done on the local system, under
36 the control of the remote system. When input editing or character echo‐
37 ing is to be disabled, the remote system will relay that information.
38 The remote system will also relay changes to any special characters
39 that happen on the remote system, so that they can take effect on the
40 local system.
41 In "character at a time" mode, most text typed is immediately sent to
44 the remote host for processing.
45 In "old line by line" mode, all text is echoed locally, and (normally)
48 only completed lines are sent to the remote host. The "local echo char‐
49 acter" (initially ^E) may be used to turn off and on the local echo.
50 (Use this mostly to enter passwords without the password being
51 echoed.).
52 If the "line mode" option is enabled, or if the localchars toggle is
55 TRUE (the default in "old line by line" mode), the user's quit, intr,
56 and flush characters are trapped locally, and sent as TELNET protocol
57 sequences to the remote side. If "line mode" has ever been enabled,
58 then the user's susp and eof are also sent as TELNET protocol
59 sequences. quit is then sent as a TELNET ABORT instead of BREAK. The
60 options toggle autoflush and toggle autosynch cause this action to
61 flush subsequent output to the terminal (until the remote host acknowl‐
62 edges the TELNET sequence); and to flush previous terminal input, in
63 the case of quit and intr.
64 While connected to a remote host, the user can enter telnet command
67 mode by typing the telnet escape character (initially ^]). When in com‐
68 mand mode, the normal terminal editing conventions are available.
69 Pressing RETURN at the telnet command prompt causes telnet to exit com‐
70 mand mode.
71
73 The following options are supported:
74 -8
76 Specifies an 8-bit data path. Negotiating the TELNET BINARY option
78 is attempted for both input and output.
79 -a
82 Attempts automatic login. This sends the user name by means of the
84 USER variable of the ENVIRON option, if supported by the remote
85 system. The name used is that of the current user as returned by
86 getlogin(3C) if it agrees with the current user ID. Otherwise, it
87 is the name associated with the user ID.
88 -c
91 Disables the reading of the user's telnetrc file. (See the toggle
93 skiprc command on this reference page.)
94 -d
97 Sets the initial value of the debug toggle to TRUE.
99 -e escape_char
102 Sets the initial escape character to escape_char. escape_char may
104 also be a two character sequence consisting of ^ (Control key) fol‐
105 lowed by one character. If the second character is ?, the DEL char‐
106 acter is selected. Otherwise, the second character is converted to
107 a control character and used as the escape character. If
108 escape_char is defined as the null string (that is, -e ''), this is
109 equivalent to -e '^@' (Control-@). To specify that no character can
110 be the escape character, use the -E option.
111 -E
114 Stops any character from being recognized as an escape character.
116 -f
119 Forwards a copy of the local credentials to the remote system.
121 -F
124 Forwards a forwardable copy of the local credentials to the remote
126 system.
127 -k realm
130 If Kerberos authentication is being used, requests that telnet
132 obtain tickets for the remote host in realm instead of the remote
133 host's default realm as determined inkrb5.conf(4).
134 -K
137 Specifies no automatic login to the remote system.
139 -l user
142 When connecting to a remote system that understands the ENVIRON
144 option, then user will be sent to the remote system as the value
145 for the ENVIRON variable USER.
146 -L
149 Specifies an 8-bit data path on output. This causes the BINARY
151 option to be negotiated on output.
152 -n tracefile
155 Opens tracefile for recording trace information. See the set trace‐
157 file command below.
158 -r
161 Specifies a user interface similar to rlogin. In this mode, the
163 escape character is set to the tilde (~) character, unless modified
164 by the -e option. The rlogin escape character is only recognized
165 when it is preceded by a carriage return. In this mode, the telnet
166 escape character, normally '^]', must still precede a telnet com‐
167 mand. The rlogin escape character can also be followed by '.\r' or
168 '^Z', and, like rlogin(1), closes or suspends the connection,
169 respectively. This option is an uncommitted interface and may
170 change in the future.
171 -x
174 Turns on encryption of the data stream. When this option is turned
176 on, telnet will exit with an error if authentication cannot be
177 negotiated or if encryption cannot be turned on.
178 -X atype
181 Disables the atype type of authentication.
183
186 telnet Commands
187 The commands described in this section are available with telnet. It is
188 necessary to type only enough of each command to uniquely identify it.
189 (This is also true for arguments to the mode, set, toggle, unset, envi‐
190 ron, and display commands.)
191 auth argument ...
193 The auth command manipulates the information sent through the TEL‐
195 NET AUTHENTICATE option. Valid arguments for the auth command are
196 as follows:
197 disable type
199 Disables the specified type of authentication. To obtain a list
201 of available types, use the auth disable ? command.
202 enable type
205 Enables the specified type of authentication. To obtain a list
207 of available types, use the auth enable ? command.
208 status
211 Lists the current status of the various types of authentica‐
213 tion.
214 open [-l user ] [ [!] @hop1 [@hop2 ...]@host [ port ]
218 Open a connection to the named host. If no port number is speci‐
220 fied, telnet will attempt to contact a TELNET server at the default
221 port. The host specification may be either a host name (see
222 hosts(4)) or an Internet address specified in the "dot notation"
223 (see inet(7P) or inet6(7P)). If the host is specified as
224 @hop1@hop2@host, the connection goes through hosts hop1 and hop2,
225 using loose source routing to end at host. The @ symbol is required
226 as a separator between the hosts specified. If a leading ! is used
227 with IPv4, the connection follows strict source routing.
228 The -l option passes the user as the value of the ENVIRON variable
230 USER to the remote system.
231 close
234 Close any open TELNET session and exit telnet. An EOF (in command
236 mode) will also close a session and exit.
237 encrypt
240 The encrypt command manipulates the information sent through the
242 TELNET ENCRYPT option.
243 Valid arguments for the encrypt command are as follows:
245 disable type [input|output]
247 Disables the specified type of encryption. If you omit the
249 input and output, both input and output are disabled. To obtain
250 a list of available types, use the encrypt disable ? command.
251 enable type [input|output]
254 Enables the specified type of encryption. If you omit input and
256 output, both input and output are enabled. To obtain a list of
257 available types, use the encrypt enable ? command.
258 input
261 This is the same as the encrypt start input command.
263 -input
266 This is the same as the encrypt stop input command.
268 output
271 This is the same as the encrypt start output command.
273 -output
276 This is the same as the encrypt stop output command.
278 start [input|output]
281 Attempts to start encryption. If you omit input and output,
283 both input and output are enabled. To obtain a list of avail‐
284 able types, use the encrypt enable ? command.
285 status
288 Lists the current status of encryption.
290 stop [input|output]
293 Stops encryption. If you omit input and output, encryption is
295 on both input and output.
296 type type
299 Sets the default type of encryption to be used with later
301 encrypt start or encrypt stop commands.
302 quit
306 Same as close.
308 z
311 Suspend telnet. This command only works when the user is using a
313 shell that supports job control, such as sh(1).
314 mode type
317 The remote host is asked for permission to go into the requested
319 mode. If the remote host is capable of entering that mode, the
320 requested mode will be entered. The argument type is one of the
321 following:
322 character
324 Disable the TELNET LINEMODE option, or, if the remote side does
326 not understand the LINEMODE option, then enter "character at a
327 time" mode.
328 line
331 Enable the TELNET LINEMODE option, or, if the remote side does
333 not understand the LINEMODE option, then attempt to enter "old-
334 line-by-line" mode.
335 isig (-isig)
338 Attempt to enable (disable) the TRAPSIG mode of the LINEMODE
340 option. This requires that the LINEMODE option be enabled.
341 edit (-edit)
344 Attempt to enable (disable) the EDIT mode of the LINEMODE
346 option. This requires that the LINEMODE option be enabled.
347 softtabs (-softtabs)
350 Attempt to enable (disable) the SOFT_TAB mode of the LINEMODE
352 option. This requires that the LINEMODE option be enabled.
353 litecho (-litecho)
356 Attempt to enable (disable) the LIT_ECHO mode of the LINEMODE
358 option. This requires that the LINEMODE option be enabled.
359 ?
362 Prints out help information for the mode command.
364 status
368 Show the current status of telnet. This includes the peer one is
370 connected to, as well as the current mode.
371 display
374 [argument...] Display all, or some, of the set and toggle values
376 (see toggle argument...).
377 ?
380 [command] Get help. With no arguments, telnet prints a help sum‐
382 mary. If a command is specified, telnet will print the help infor‐
383 mation for just that command.
384 send argument...
387 Send one or more special character sequences to the remote host.
389 The following are the arguments that can be specified (more than
390 one argument may be specified at a time):
391 escape
393 Send the current telnet escape character (initially ^]).
395 synch
398 Send the TELNET SYNCH sequence. This sequence discards all pre‐
400 viously typed, but not yet read, input on the remote system.
401 This sequence is sent as TCP urgent data and may not work if
402 the remote system is a 4.2 BSD system. If it does not work, a
403 lowercase "r" may be echoed on the terminal.
404 brk or break
407 Send the TELNET BRK (Break) sequence, which may have signifi‐
409 cance to the remote system.
410 ip
413 Send the TELNET IP (Interrupt Process) sequence, which aborts
415 the currently running process on the remote system.
416 abort
419 Send the TELNET ABORT (Abort Process) sequence.
421 ao
424 Send the TELNET AO (Abort Output) sequence, which flushes all
426 output from the remote system to the user's terminal.
427 ayt
430 Send the TELNET AYT (Are You There) sequence, to which the
432 remote system may or may not respond.
433 ec
436 Send the TELNET EC (Erase Character) sequence, which erases the
438 last character entered.
439 el
442 Send the TELNET EL (Erase Line) sequence, which should cause
444 the remote system to erase the line currently being entered.
445 eof
448 Send the TELNET EOF (End Of File) sequence.
450 eor
453 Send the TELNET EOR (End Of Record) sequence.
455 ga
458 Send the TELNET GA (Go Ahead) sequence, which probably has no
460 significance for the remote system.
461 getstatus
464 If the remote side supports the TELNET STATUS command, getsta‐
466 tus will send the subnegotiation to request that the server
467 send its current option status.
468 nop
471 Send the TELNET NOP (No Operation) sequence.
473 susp
476 Send the TELNET SUSP (Suspend Process) sequence.
478 do option
481 dont option
482 will option
483 wont option
484 Send the TELNET protocol option negotiation indicated. Option
486 may be the text name of the protocol option, or the number cor‐
487 responding to the option. The command will be silently ignored
488 if the option negotiation indicated is not valid in the current
489 state. If the option is given as help or ?, the list of option
490 names known is listed. This command is mostly useful for
491 unusual debugging situations.
492 ?
495 Print out help information for the send command.
497 set argument [value]
501 unset argument
502 Set any one of a number of telnet variables to a specific value.
504 The special value off turns off the function associated with the
505 variable. The values of variables may be interrogated with the dis‐
506 play command. If value is omitted, the value is taken to be true,
507 or "on". If the unset form is used, the value is taken to be false,
508 or off. The variables that may be specified are:
509 echo
511 This is the value (initially ^E) that, when in "line by line"
513 mode, toggles between local echoing of entered characters for
514 normal processing, and suppressing echoing of entered charac‐
515 ters, for example, entering a password.
516 escape
519 This is the telnet escape character (initially ^]) that enters
521 telnet command mode when connected to a remote system.
522 interrupt
525 If telnet is in localchars mode (see toggle, localchars) and
527 the interrupt character is typed, a TELNET IP sequence (see
528 send and ip) is sent to the remote host. The initial value for
529 the interrupt character is taken to be the terminal's intr
530 character.
531 quit
534 If telnet is in localchars mode and the quit character is
536 typed, a TELNET BRK sequence (see send, brk) is sent to the
537 remote host. The initial value for the quit character is taken
538 to be the terminal's quit character.
539 flushoutput
542 If telnet is in localchars mode and the flushoutput character
544 is typed, a TELNET AO sequence (see send, ao) is sent to the
545 remote host. The initial value for the flush character is taken
546 to be the terminal's flush character.
547 erase
550 If telnet is in localchars mode and operating in "character at
552 a time" mode, then when the erase character is typed, a TELNET
553 EC sequence (see send, ec) is sent to the remote system. The
554 initial value for the erase character is taken to be the termi‐
555 nal's erase character.
556 kill
559 If telnet is in localchars mode and operating in "character at
561 a time" mode, then when the kill character is typed, a TELNET
562 EL sequence (see send, el) is sent to the remote system. The
563 initial value for the kill character is taken to be the termi‐
564 nal's kill character.
565 eof
568 If telnet is operating in "line by line"/ mode, entering the
570 eof character as the first character on a line sends this char‐
571 acter to the remote system. The initial value of eof is taken
572 to be the terminal's eof character.
573 ayt
576 If telnet is in localchars mode, or LINEMODE is enabled, and
578 the status character is typed, a TELNET AYT ("Are You There")
579 sequence is sent to the remote host. (See send, ayt above.) The
580 initial value for ayt is the terminal's status character.
581 forw1
584 forw2
585 If telnet is operating in LINEMODE, and the forw1 or forw2
587 characters are typed, this causes the forwarding of partial
588 lines to the remote system. The initial values for the forward‐
589 ing characters come from the terminal's eol and eol2 charac‐
590 ters.
591 lnext
594 If telnet is operating in LINEMODE or "old line by line" mode,
596 then the lnext character is assumed to be the terminal's lnext
597 character. The initial value for the lnext character is taken
598 to be the terminal's lnext character.
599 reprint
602 If telnet is operating in LINEMODE or "old line by line" mode,
604 then the reprint character is assumed to be the terminal's re‐
605 print character. The initial value for reprint is taken to be
606 the terminal's reprint character.
607 rlogin
610 This is the rlogin escape character. If set, the normal telnet
612 escape character is ignored, unless it is preceded by this
613 character at the beginning of a line. The rlogin character, at
614 the beginning of a line followed by a "." closes the connec‐
615 tion. When followed by a ^Z, the rlogin command suspends the
616 telnet command. The initial state is to disable the rlogin
617 escape character.
618 start
621 If the TELNET TOGGLE-FLOW-CONTROL option has been enabled, then
623 the start character is taken to be the terminal's start charac‐
624 ter. The initial value for the kill character is taken to be
625 the terminal's start character.
626 stop
629 If the TELNET TOGGLE-FLOW-CONTROL option has been enabled, then
631 the stop character is taken to be the terminal's stop charac‐
632 ter. The initial value for the kill character is taken to be
633 the terminal's stop character.
634 susp
637 If telnet is in localchars mode, or LINEMODE is enabled, and
639 the suspend character is typed, a TELNET SUSP sequence (see
640 send, susp above) is sent to the remote host. The initial value
641 for the suspend character is taken to be the terminal's suspend
642 character.
643 tracefile
646 This is the file to which the output, generated when the net‐
648 data or the debug option is TRUE, will be written. If tracefile
649 is set to "-", then tracing information will be written to
650 standard output (the default).
651 worderase
654 If telnet is operating in LINEMODE or "old line by line" mode,
656 then this character is taken to be the terminal's worderase
657 character. The initial value for the worderase character is
658 taken to be the terminal's worderase character.
659 ?
662 Displays the legal set and unset commands.
664 slc state
668 The slc (Set Local Characters) command is used to set or change the
670 state of special characters when the TELNET LINEMODE option has
671 been enabled. Special characters are characters that get mapped to
672 TELNET commands sequences (like ip or quit) or line editing charac‐
673 ters (like erase and kill). By default, the local special charac‐
674 ters are exported. The following values for state are valid:
675 check
677 Verifies the settings for the current special characters. The
679 remote side is requested to send all the current special char‐
680 acter settings. If there are any discrepancies with the local
681 side, the local settings will switch to the remote values.
682 export
685 Switches to the local defaults for the special characters. The
687 local default characters are those of the local terminal at the
688 time when telnet was started.
689 import
692 Switches to the remote defaults for the special characters. The
694 remote default characters are those of the remote system at the
695 time when the TELNET connection was established.
696 ?
699 Prints out help information for the slc command.
701 toggle argument...
705 Toggle between TRUE and FALSE the various flags that control how
707 telnet responds to events. More than one argument may be specified.
708 The state of these flags may be interrogated with the display com‐
709 mand. Valid arguments are:
710 authdebug Turns on debugging information for the authen‐
712 tication code.
713 autodecrypt When the TELNET ENCRYPT option is negotiated,
716 by default the actual encryption (decryption)
717 of the data stream does not start automati‐
718 cally. The autoencrypt (autodecrypt) command
719 states that encryption of the output (input)
720 stream should be enabled as soon as possible.
721 autologin If the remote side supports the TELNET AUTHEN‐
724 TICATION option, telnet attempts to use it to
725 perform automatic authentication. If the
726 AUTHENTICATION option is not supported, the
727 user's login name is propagated through the
728 TELNET ENVIRON option. This command is the same
729 as specifying the -a option on the open com‐
730 mand.
731 autoflush If autoflush and localchars are both TRUE, then
734 when the ao, intr, or quit characters are rec‐
735 ognized (and transformed into TELNET sequences;
736 see set for details), telnet refuses to display
737 any data on the user's terminal until the
738 remote system acknowledges (using a TELNET Tim‐
739 ing Mark option) that it has processed those
740 TELNET sequences. The initial value for this
741 toggle is TRUE if the terminal user has not
742 done an "stty noflsh". Otherwise, the value is
743 FALSE (see stty(1)).
744 autosynch If autosynch and localchars are both TRUE, then
747 when either the interrupt or quit characters
748 are typed (see set for descriptions of inter‐
749 rupt and quit), the resulting TELNET sequence
750 sent is followed by the TELNET SYNCH sequence.
751 This procedure should cause the remote system
752 to begin throwing away all previously typed
753 input until both of the TELNET sequences have
754 been read and acted upon. The initial value of
755 this toggle is FALSE.
756 binary Enable or disable the TELNET BINARY option on
759 both input and output.
760 inbinary Enable or disable the TELNET BINARY option on
763 input.
764 outbinary Enable or disable the TELNET BINARY option on
767 output.
768 crlf Determines how carriage returns are sent. If
771 the value is TRUE, then carriage returns will
772 be sent as <CR><LF>. If the value is FALSE,
773 then carriage returns will be send as
774 <CR><NUL>. The initial value for this toggle is
775 FALSE.
776 crmod Toggle RETURN mode. When this mode is enabled,
779 most RETURN characters received from the remote
780 host will be mapped into a RETURN followed by a
781 line feed. This mode does not affect those
782 characters typed by the user, only those
783 received from the remote host. This mode is
784 useful only for remote hosts that send RETURN
785 but never send LINEFEED. The initial value for
786 this toggle is FALSE.
787 debug Toggle socket level debugging (only available
790 to the super-user). The initial value for this
791 toggle is FALSE.
792 encdebug Turns on debugging information for the encryp‐
795 tion code.
796 localchars If this toggle is TRUE, then the flush, inter‐
799 rupt, quit, erase, and kill characters (see
800 set) are recognized locally, and transformed
801 into appropriate TELNET control sequences,
802 respectively ao, ip, brk, ec, and el (see
803 send). The initial value for this toggle is
804 TRUE in "line by line" mode, and FALSE in
805 "character at a time" mode. When the LINEMODE
806 option is enabled, the value of localchars is
807 ignored, and assumed always to be TRUE. If
808 LINEMODE has ever been enabled, then quit is
809 sent as abort, and eof and suspend are sent as
810 eof and susp (see send above).
811 netdata Toggle the display of all network data (in
814 hexadecimal format). The initial value for this
815 toggle is FALSE.
816 options Toggle the display of some internal TELNET pro‐
819 tocol processing (having to do with telnet
820 options). The initial value for this toggle is
821 FALSE.
822 prettydump When the netdata toggle is enabled, if pretty‐
825 dump is enabled, the output from the netdata
826 command will be formatted in a more user read‐
827 able format. Spaces are put between each char‐
828 acter in the output. The beginning of any TEL‐
829 NET escape sequence is preceded by an asterisk
830 (*) to aid in locating them.
831 skiprc When the skiprc toggle is TRUE, TELNET skips
834 the reading of the .telnetrc file in the user's
835 home directory when connections are opened. The
836 initial value for this toggle is FALSE.
837 termdata Toggles the display of all terminal data (in
840 hexadecimal format). The initial value for this
841 toggle is FALSE.
842 verbose_encrypt When the verbose_encrypt flag is TRUE, TELNET
845 prints out a message each time encryption is
846 enabled or disabled. The initial value for this
847 toggle is FALSE.
848 ? Display the legal toggle commands.
851 environ argument...
855 The environ command is used to manipulate variables that may be
857 sent through the TELNET ENVIRON option. The initial set of vari‐
858 ables is taken from the users environment. Only the DISPLAY and
859 PRINTER variables are exported by default. Valid arguments for the
860 environ command are:
861 define variable value
863 Define variable to have a value of value. Any variables defined
865 by this command are automatically exported. The value may be
866 enclosed in single or double quotes, so that tabs and spaces
867 may be included.
868 undefine variable
871 Remove variable from the list of environment variables.
873 export variable
876 Mark the variable to be exported to the remote side.
878 unexport variable
881 Mark the variable to not be exported unless explicitly
883 requested by the remote side.
884 list
887 List the current set of environment variables. Those marked
889 with an asterisk (*) will be sent automatically. Other vari‐
890 ables will be sent only if explicitly requested.
891 ?
894 Prints out help information for the environ command.
896 logout
900 Sends the telnet logout option to the remote side. This command is
902 similar to a close command. However, if the remote side does not
903 support the logout option, nothing happens. If, however, the remote
904 side does support the logout option, this command should cause the
905 remote side to close the TELNET connection. If the remote side also
906 supports the concept of suspending a user's session for later reat‐
907 tachment, the logout argument indicates that the remote side should
908 terminate the session immediately.
909
912 $HOME/.telnetrc file that contains commands to be executed before
913 initiating a telnet session
914
917 See attributes(5) for descriptions of the following attributes:
918 ┌─────────────────────────────┬─────────────────────────────┐
923 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
924 ├─────────────────────────────┼─────────────────────────────┤
925 │Availability │SUNWtnetc │
926 └─────────────────────────────┴─────────────────────────────┘
927
929 rlogin(1), sh(1), stty(1), getlogin(3C), hosts(4), krb5.conf(4), nolo‐
930 gin(4), telnetrc(4), attributes(5), inet(7P), inet6(7P)
931
933 NO LOGINS: System going down in N minutes
934 The machine is in the process of being shut down and logins have
936 been disabled.
937
940 On some remote systems, echo has to be turned off manually when in
941 "line by line" mode.
942 In "old line by line" mode, or LINEMODE, the terminal's EOF character
945 is only recognized (and sent to the remote system) when it is the first
946 character on a line.
947 The telnet protocol only uses single DES for session protection—clients
950 request service tickets with single DES session keys. The KDC must know
951 that host service principals that offer the telnet service support sin‐
952 gle DES, which, in practice, means that such principals must have sin‐
953 gle DES keys in the KDC database.
954SunOS 5.11 17 Aug 2006 telnet(1)