| blob | fa946c3ecdd84f63d7e4dfb7da12440c84fa3f74 |
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30 .\" from: @(#)telnet.1 8.4 (Berkeley) 2/3/94
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32 .Dd October 28, 2003
33 .Dt TELNET 1
34 .Os
35 .Sh NAME
36 .Nm telnet
37 .Nd user interface to the
38 .Tn TELNET
39 protocol
40 .Sh SYNOPSIS
41 .Nm
42 .Op Fl 468acdEFfKLNrx
43 .Op Fl e Ar escapechar
44 .Op Fl k Ar realm
45 .Op Fl l Ar user
46 .Op Fl n Ar tracefile
47 .Op Fl P Ar policy
48 .Op Fl S Ar tos
49 .Op Fl X Ar authtype
50 .Oo
51 .Ar host
52 .Op Ar port
53 .Oc
54 .Sh DESCRIPTION
55 The
56 .Nm
57 command
58 is used to communicate with another host using the
59 .Tn TELNET
60 protocol.
61 If
62 .Nm
63 is invoked without the
64 .Ar host
65 argument, it enters command mode,
66 indicated by its prompt
67 .Pq Nm telnet\&\*[Gt] .
68 In this mode, it accepts and executes the commands listed below.
69 If it is invoked with arguments, it performs an
70 .Ic open
71 command with those arguments.
72 .Pp
73 Options:
74 .Bl -tag -width indent
75 .It Fl 4
76 Forces
77 .Nm
78 to use IPv4 addresses only.
79 .It Fl 6
80 Forces
81 .Nm
82 to use IPv6 addresses only.
83 .It Fl 8
84 Specifies an 8-bit data path.
85 This causes an attempt to
86 negotiate the
87 .Dv TELNET BINARY
88 option on both input and output.
89 .It Fl E
90 Stops any character from being recognized as an escape character.
91 .It Fl F
92 If Kerberos V5 authentication is being used, the
93 .Fl F
94 option allows the local credentials to be forwarded
95 to the remote system, including any credentials that
96 have already been forwarded into the local environment.
97 .It Fl K
98 Specifies no automatic login to the remote system.
99 .It Fl L
100 Specifies an 8-bit data path on output.
101 This causes the
102 BINARY option to be negotiated on output.
103 .It Fl N
104 Numeric host address.
105 No attempt will be made to look up
106 symbolic names for host addresses.
107 .It Fl S Ar tos
108 Sets the IP type-of-service (TOS) option for the telnet
109 connection to the value
110 .Ar tos ,
111 which can be a numeric TOS value
112 or, on systems that support it, a symbolic
113 TOS name found in the /etc/iptos file.
114 .It Fl X Ar atype
115 Disables the
116 .Ar atype
117 type of authentication.
118 .It Fl a
119 Attempt automatic login.
120 Currently, this sends the user name via the
121 .Ev USER
122 variable
123 of the
124 .Ev ENVIRON
125 option if supported by the remote system.
126 The name used is that of the current user as returned by
127 .Xr getlogin 2
128 if it agrees with the current user ID,
129 otherwise it is the name associated with the user ID.
130 .It Fl c
131 Disables the reading of the user's
132 .Pa \&.telnetrc
133 file.
134 (See the
135 .Ic toggle skiprc
136 command on this man page.)
137 .It Fl d
138 Sets the initial value of the
139 .Ic debug
140 toggle to
141 .Dv TRUE .
142 .It Fl e Ar escape char
143 Sets the initial
144 .Nm
145 escape character to
146 .Ar escape char .
147 If
148 .Ar escape char
149 is omitted, then
150 there will be no escape character.
151 .It Fl f
152 If Kerberos V5 authentication is being used, the
153 .Fl f
154 option allows the local credentials to be forwarded to the remote system.
155 .It Fl k Ar realm
156 If Kerberos authentication is being used, the
157 .Fl k
158 option requests that telnet obtain tickets for the remote host in
159 realm
160 .Ar realm
161 instead of the remote host's realm, as determined by
162 .Xr krb_realmofhost 3 .
163 .It Fl l Ar user
164 When connecting to the remote system, if the remote system
165 understands the
166 .Ev ENVIRON
167 option, then
168 .Ar user
169 will be sent to the remote system as the value for the variable USER.
170 This option implies the
171 .Fl a
172 option.
173 This option may also be used with the
174 .Ic open
175 command.
176 .It Fl n Ar tracefile
177 Opens
178 .Ar tracefile
179 for recording trace information.
180 See the
181 .Ic set tracefile
182 command below.
183 .It Fl P Ar policy
184 Use IPsec policy specification string
185 .Ar policy ,
186 for the connections.
187 See
188 .Xr ipsec_set_policy 3
189 for details.
190 .It Fl r
191 Specifies a user interface similar to
192 .Xr rlogin 1 .
193 In this
194 mode, the escape character is set to the tilde (~) character,
195 unless modified by the
196 .Fl e
197 option.
198 .It Fl x
199 Turns on encryption of the data stream if possible.
200 This
201 option is not available outside of the United States and
202 Canada.
203 .It Ar host
204 Indicates the official name, an alias, or the Internet address
205 of a remote host.
206 .It Ar port
207 Indicates a port number (address of an application).
208 If a number is
209 not specified, the default
210 .Nm
211 port is used.
212 .El
213 .Pp
214 When in rlogin mode, a line of the form ~.
215 disconnects from the
216 remote host; ~ is the telnet escape character.
217 Similarly, the line ~^Z suspends the telnet session.
218 The line ~^] escapes to the normal telnet escape prompt.
219 .Pp
220 Once a connection has been opened,
221 .Nm
222 will attempt to enable the
223 .Dv TELNET LINEMODE
224 option.
225 If this fails, then
226 .Nm
227 will revert to one of two input modes:
228 either \*(Lqcharacter at a time\*(Rq
229 or \*(Lqold line by line\*(Rq
230 depending on what the remote system supports.
231 .Pp
232 When
233 .Dv LINEMODE
234 is enabled, character processing is done on the
235 local system, under the control of the remote system.
236 When input
237 editing or character echoing is to be disabled, the remote system
238 will relay that information.
239 The remote system will also relay
240 changes to any special characters that happen on the remote
241 system, so that they can take effect on the local system.
242 .Pp
243 In \*(Lqcharacter at a time\*(Rq mode, most
244 text typed is immediately sent to the remote host for processing.
245 .Pp
246 In \*(Lqold line by line\*(Rq mode, all text is echoed locally,
247 and (normally) only completed lines are sent to the remote host.
248 The \*(Lqlocal echo character\*(Rq (initially \*(Lq^E\*(Rq) may be used
249 to turn off and on the local echo
250 (this would mostly be used to enter passwords
251 without the password being echoed).
252 .Pp
253 If the
254 .Dv LINEMODE
255 option is enabled, or if the
256 .Ic localchars
257 toggle is
258 .Dv TRUE
259 (the default for \*(Lqold line by line\*(Lq; see below),
260 the user's
261 .Ic quit ,
262 .Ic intr ,
263 and
264 .Ic flush
265 characters are trapped locally, and sent as
266 .Tn TELNET
267 protocol sequences to the remote side.
268 If
269 .Dv LINEMODE
270 has ever been enabled, then the user's
271 .Ic susp
272 and
273 .Ic eof
274 are also sent as
275 .Tn TELNET
276 protocol sequences,
277 and
278 .Ic quit
279 is sent as a
280 .Dv TELNET ABORT
281 instead of
282 .Dv BREAK .
283 There are options (see
284 .Ic toggle
285 .Ic autoflush
286 and
287 .Ic toggle
288 .Ic autosynch
289 below)
290 which cause this action to flush subsequent output to the terminal
291 (until the remote host acknowledges the
292 .Tn TELNET
293 sequence) and flush previous terminal input
294 (in the case of
295 .Ic quit
296 and
297 .Ic intr ) .
298 .Pp
299 While connected to a remote host,
300 .Nm
301 command mode may be entered by typing the
302 .Nm
303 \*(Lqescape character\*(Rq (initially \*(Lq^]\*(Rq).
304 When in command mode, the normal terminal editing conventions are available.
305 .Pp
306 The following
307 .Nm
308 commands are available.
309 Only enough of each command to uniquely identify it need be typed
310 (this is also true for arguments to the
311 .Ic mode ,
312 .Ic set ,
313 .Ic toggle ,
314 .Ic unset ,
315 .Ic slc ,
316 .Ic environ ,
317 and
318 .Ic display
319 commands).
320 .Pp
321 .Bl -tag -width "mode type"
322 .It Ic auth Ar argument ...
323 The auth command manipulates the information sent through the
324 .Dv TELNET AUTHENTICATE
325 option.
326 Valid arguments for the
327 auth command are as follows:
328 .Bl -tag -width "disable type"
329 .It Ic disable Ar type
330 Disables the specified type of authentication.
331 To obtain a list of available types, use the
332 .Ic auth disable \&?
333 command.
334 .It Ic enable Ar type
335 Enables the specified type of authentication.
336 To obtain a list of available types, use the
337 .Ic auth enable \&?
338 command.
339 .It Ic status
340 Lists the current status of the various types of
341 authentication.
342 .El
343 .It Ic close
344 Close a
345 .Tn TELNET
346 session and return to command mode.
347 .It Ic display Ar argument ...
348 Displays all, or some, of the
349 .Ic set
350 and
351 .Ic toggle
352 values (see below).
353 .It Ic encrypt Ar argument ...
354 The encrypt command manipulates the information sent through the
355 .Dv TELNET ENCRYPT
356 option.
357 .Pp
358 Note: Because of export controls, the
359 .Dv TELNET ENCRYPT
360 option is not supported outside of the United States and Canada.
361 .Pp
362 Valid arguments for the encrypt command are:
363 .Bl -tag -width Ar
364 .It Ic disable Ar type Ic [input|output]
365 Disables the specified type of encryption.
366 If you omit the input and output, both input and output
367 are disabled.
368 To obtain a list of available types, use the
369 .Ic encrypt disable \&?
370 command.
371 .It Ic enable Ar type Ic [input|output]
372 Enables the specified type of encryption.
373 If you omit input and output, both input and output are
374 enabled.
375 To obtain a list of available types, use the
376 .Ic encrypt enable \&?
377 command.
378 .It Ic input
379 This is the same as the
380 .Ic encrypt start input
381 command.
382 .It Ic -input
383 This is the same as the
384 .Ic encrypt stop input
385 command.
386 .It Ic output
387 This is the same as the
388 .Ic encrypt start output
389 command.
390 .It Ic -output
391 This is the same as the
392 .Ic encrypt stop output
393 command.
394 .It Ic start Ic [input|output]
395 Attempts to start encryption.
396 If you omit
397 .Ic input
398 and
399 .Ic output ,
400 both input and output are enabled.
401 To obtain a list of available types, use the
402 .Ic encrypt enable \&?
403 command.
404 .It Ic status
405 Lists the current status of encryption.
406 .It Ic stop Ic [input|output]
407 Stops encryption.
408 If you omit input and output,
409 encryption is on both input and output.
410 .It Ic type Ar type
411 Sets the default type of encryption to be used
412 with later
413 .Ic encrypt start
414 or
415 .Ic encrypt stop
416 commands.
417 .El
418 .It Ic environ Ar arguments ...
419 The
420 .Ic environ
421 command is used to manipulate the
422 variables that may be sent through the
423 .Dv TELNET ENVIRON
424 option.
425 The initial set of variables is taken from the users
426 environment, with only the
427 .Ev DISPLAY
428 and
429 .Ev PRINTER
430 variables being exported by default.
431 The
432 .Ev USER
433 variable is also exported if the
434 .Fl a
435 or
436 .Fl l
437 options are used.
438 .Pp
439 Valid arguments for the
440 .Ic environ
441 command are:
442 .Bl -tag -width Fl
443 .It Ic define Ar variable value
444 Define the variable
445 .Ar variable
446 to have a value of
447 .Ar value .
448 Any variables defined by this command are automatically exported.
449 The
450 .Ar value
451 may be enclosed in single or double quotes so
452 that tabs and spaces may be included.
453 .It Ic undefine Ar variable
454 Remove
455 .Ar variable
456 from the list of environment variables.
457 .It Ic export Ar variable
458 Mark the variable
459 .Ar variable
460 to be exported to the remote side.
461 .It Ic unexport Ar variable
462 Mark the variable
463 .Ar variable
464 to not be exported unless
465 explicitly asked for by the remote side.
466 .It Ic list
467 List the current set of environment variables.
468 Those marked with a
469 .Cm *
470 will be sent automatically,
471 other variables will only be sent if explicitly requested.
472 .It Ic \&?
473 Prints out help information for the
474 .Ic environ
475 command.
476 .El
477 .It Ic logout
478 Sends the
479 .Dv TELNET LOGOUT
480 option to the remote side.
481 This command is similar to a
482 .Ic close
483 command; however, if the remote side does not support the
484 .Dv LOGOUT
485 option, nothing happens.
486 If, however, the remote side does support the
487 .Dv LOGOUT
488 option, this command should cause the remote side to close the
489 .Tn TELNET
490 connection.
491 If the remote side also supports the concept of
492 suspending a user's session for later reattachment,
493 the logout argument indicates that you
494 should terminate the session immediately.
495 .It Ic mode Ar type
496 .Ar Type
497 is one of several options, depending on the state of the
498 .Tn TELNET
499 session.
500 The remote host is asked for permission to go into the requested mode.
501 If the remote host is capable of entering that mode, the requested
502 mode will be entered.
503 .Bl -tag -width Ar
504 .It Ic character
505 Disable the
506 .Dv TELNET LINEMODE
507 option, or, if the remote side does not understand the
508 .Dv LINEMODE
509 option, then enter \*(Lqcharacter at a time\*(Lq mode.
510 .It Ic line
511 Enable the
512 .Dv TELNET LINEMODE
513 option, or, if the remote side does not understand the
514 .Dv LINEMODE
515 option, then attempt to enter \*(Lqold-line-by-line\*(Lq mode.
516 .It Ic isig Pq Ic \-isig
517 Attempt to enable (disable) the
518 .Dv TRAPSIG
519 mode of the
520 .Dv LINEMODE
521 option.
522 This requires that the
523 .Dv LINEMODE
524 option be enabled.
525 .It Ic edit Pq Ic \-edit
526 Attempt to enable (disable) the
527 .Dv EDIT
528 mode of the
529 .Dv LINEMODE
530 option.
531 This requires that the
532 .Dv LINEMODE
533 option be enabled.
534 .It Ic softtabs Pq Ic \-softtabs
535 Attempt to enable (disable) the
536 .Dv SOFT_TAB
537 mode of the
538 .Dv LINEMODE
539 option.
540 This requires that the
541 .Dv LINEMODE
542 option be enabled.
543 .It Ic litecho Pq Ic \-litecho
544 Attempt to enable (disable) the
545 .Dv LIT_ECHO
546 mode of the
547 .Dv LINEMODE
548 option.
549 This requires that the
550 .Dv LINEMODE
551 option be enabled.
552 .It Ic \&?
553 Prints out help information for the
554 .Ic mode
555 command.
556 .El
557 .It Ic open Ar host Oo Fl l Ar user Oc Oo Fl a Oc Oo Oo \&- Oc Ns Ar port Oc
558 Open a connection to the named host.
559 If no port number
560 is specified,
561 .Nm
562 will attempt to contact a
563 .Tn TELNET
564 server at the default port.
565 The host specification may be either a host name (see
566 .Xr hosts 5 )
567 or an Internet address specified in the \*(Lqdot notation\*(Rq (see
568 .Xr inet 3 ) .
569 The
570 .Fl l
571 option may be used to specify the user name
572 to be passed to the remote system via the
573 .Ev ENVIRON
574 option.
575 If a port is specified
576 .Nm
577 omits any automatic initialisation of
578 .Tn TELNET
579 options.
580 When the port number is preceded by a minus sign,
581 the initial option negotiation is done.
582 .Pp
583 After establishing a connection, the file
584 .Pa \&.telnetrc
585 in the
586 user's home directory is read.
587 Lines beginning with a # are
588 comment lines.
589 Blank lines are ignored.
590 Lines that begin
591 without white space are the start of a machine entry.
592 The first thing on such a line is a string identifying the machine
593 that is being connected to.
594 It may be the hostname or numeric address specified as the argument
595 .Ar host ,
596 the canonical name of that string as determined by
597 .Xr getaddrinfo 3 ,
598 or the string
599 .Dq DEFAULT
600 indicating all hosts.
601 The rest of the line, and successive
602 lines that begin with white space are assumed to be
603 .Nm
604 commands and are processed as if they had been typed
605 in manually to the
606 .Nm
607 command prompt.
608 .It Ic quit
609 Close any open
610 .Tn TELNET
611 session and exit
612 .Nm .
613 An end of file (in command mode) will also close a session and exit.
614 .It Ic send Ar arguments
615 Sends one or more special character sequences to the remote host.
616 The following are the arguments which may be specified
617 (more than one argument may be specified at a time):
618 .Pp
619 .Bl -tag -width escape
620 .It Ic abort
621 Sends the
622 .Dv TELNET ABORT
623 (Abort
624 processes)
625 sequence.
626 .It Ic ao
627 Sends the
628 .Dv TELNET AO
629 (Abort Output) sequence, which should cause the remote system to flush
630 all output
631 .Em from
632 the remote system
633 .Em to
634 the user's terminal.
635 .It Ic ayt
636 Sends the
637 .Dv TELNET AYT
638 (Are You There)
639 sequence, to which the remote system may or may not choose to respond.
640 .It Ic brk
641 Sends the
642 .Dv TELNET BRK
643 (Break) sequence, which may have significance to the remote
644 system.
645 .It Ic ec
646 Sends the
647 .Dv TELNET EC
648 (Erase Character)
649 sequence, which should cause the remote system to erase the last character
650 entered.
651 .It Ic el
652 Sends the
653 .Dv TELNET EL
654 (Erase Line)
655 sequence, which should cause the remote system to erase the line currently
656 being entered.
657 .It Ic eof
658 Sends the
659 .Dv TELNET EOF
660 (End Of File)
661 sequence.
662 .It Ic eor
663 Sends the
664 .Dv TELNET EOR
665 (End of Record)
666 sequence.
667 .It Ic escape
668 Sends the current
669 .Nm
670 escape character (initially \*(Lq^\*(Rq).
671 .It Ic ga
672 Sends the
673 .Dv TELNET GA
674 (Go Ahead)
675 sequence, which likely has no significance to the remote system.
676 .It Ic getstatus
677 If the remote side supports the
678 .Dv TELNET STATUS
679 command,
680 .Ic getstatus
681 will send the subnegotiation to request that the server send
682 its current option status.
683 .It Ic ip
684 Sends the
685 .Dv TELNET IP
686 (Interrupt Process) sequence, which should cause the remote
687 system to abort the currently running process.
688 .It Ic nop
689 Sends the
690 .Dv TELNET NOP
691 (No OPeration)
692 sequence.
693 .It Ic susp
694 Sends the
695 .Dv TELNET SUSP
696 (SUSPend process)
697 sequence.
698 .It Ic synch
699 Sends the
700 .Dv TELNET SYNCH
701 sequence.
702 This sequence causes the remote system to discard all previously typed
703 (but not yet read) input.
704 This sequence is sent as
705 .Tn TCP
706 urgent
707 data (and may not work if the remote system is a
708 .Bx 4.2
709 system -- if
710 it doesn't work, a lower case \*(Lqr\*(Rq may be echoed on the terminal).
711 .It Ic do Ar cmd
712 .It Ic dont Ar cmd
713 .It Ic will Ar cmd
714 .It Ic wont Ar cmd
715 Sends the
716 .Dv TELNET DO
717 .Ar cmd
718 sequence.
719 .Ar Cmd
720 can be either a decimal number between 0 and 255,
721 or a symbolic name for a specific
722 .Dv TELNET
723 command.
724 .Ar Cmd
725 can also be either
726 .Ic help
727 or
728 .Ic \&?
729 to print out help information, including
730 a list of known symbolic names.
731 .It Ic \&?
732 Prints out help information for the
733 .Ic send
734 command.
735 .El
736 .It Ic set Ar argument value
737 .It Ic unset Ar argument value
738 The
739 .Ic set
740 command will set any one of a number of
741 .Nm
742 variables to a specific value or to
743 .Dv TRUE .
744 The special value
745 .Ic off
746 turns off the function associated with
747 the variable, this is equivalent to using the
748 .Ic unset
749 command.
750 The
751 .Ic unset
752 command will disable or set to
753 .Dv FALSE
754 any of the specified functions.
755 The values of variables may be interrogated with the
756 .Ic display
757 command.
758 The variables which may be set or unset, but not toggled, are
759 listed here.
760 In addition, any of the variables for the
761 .Ic toggle
762 command may be explicitly set or unset using
763 the
764 .Ic set
765 and
766 .Ic unset
767 commands.
768 .Bl -tag -width escape
769 .It Ic ayt
770 If
771 .Tn TELNET
772 is in localchars mode, or
773 .Dv LINEMODE
774 is enabled, and the status character is typed, a
775 .Dv TELNET AYT
776 sequence (see
777 .Ic send ayt
778 above) is sent to the
779 remote host.
780 The initial value for the "Are You There"
781 character is the terminal's status character.
782 .It Ic echo
783 This is the value (initially \*(Lq^E\*(Rq) which, when in
784 \*(Lqline by line\*(Rq mode, toggles between doing local echoing
785 of entered characters (for normal processing), and suppressing
786 echoing of entered characters (for entering, say, a password).
787 .It Ic eof
788 If
789 .Nm
790 is operating in
791 .Dv LINEMODE
792 or \*(Lqold line by line\*(Rq mode, entering this character
793 as the first character on a line will cause this character to be
794 sent to the remote system.
795 The initial value of the eof character is taken to be the terminal's
796 .Ic eof
797 character.
798 .It Ic erase
799 If
800 .Nm
801 is in
802 .Ic localchars
803 mode (see
804 .Ic toggle
805 .Ic localchars
806 below),
807 .Sy and
808 if
809 .Nm
810 is operating in \*(Lqcharacter at a time\*(Rq mode, then when this
811 character is typed, a
812 .Dv TELNET EC
813 sequence (see
814 .Ic send
815 .Ic ec
816 above)
817 is sent to the remote system.
818 The initial value for the erase character is taken to be
819 the terminal's
820 .Ic erase
821 character.
822 .It Ic escape
823 This is the
824 .Nm
825 escape character (initially \*(Lq^[\*(Rq) which causes entry
826 into
827 .Nm
828 command mode (when connected to a remote system).
829 .It Ic flushoutput
830 If
831 .Nm
832 is in
833 .Ic localchars
834 mode (see
835 .Ic toggle
836 .Ic localchars
837 below)
838 and the
839 .Ic flushoutput
840 character is typed, a
841 .Dv TELNET AO
842 sequence (see
843 .Ic send
844 .Ic ao
845 above)
846 is sent to the remote host.
847 The initial value for the flush character is taken to be
848 the terminal's
849 .Ic flush
850 character.
851 .It Ic forw1
852 .It Ic forw2
853 If
854 .Tn TELNET
855 is operating in
856 .Dv LINEMODE ,
857 these are the
858 characters that, when typed, cause partial lines to be
859 forwarded to the remote system.
860 The initial value for
861 the forwarding characters are taken from the terminal's
862 eol and eol2 characters.
863 .It Ic interrupt
864 If
865 .Nm
866 is in
867 .Ic localchars
868 mode (see
869 .Ic toggle
870 .Ic localchars
871 below)
872 and the
873 .Ic interrupt
874 character is typed, a
875 .Dv TELNET IP
876 sequence (see
877 .Ic send
878 .Ic ip
879 above)
880 is sent to the remote host.
881 The initial value for the interrupt character is taken to be
882 the terminal's
883 .Ic intr
884 character.
885 .It Ic kill
886 If
887 .Nm
888 is in
889 .Ic localchars
890 mode (see
891 .Ic toggle
892 .Ic localchars
893 below),
894 .Ic and
895 if
896 .Nm
897 is operating in \*(Lqcharacter at a time\*(Rq mode, then when this
898 character is typed, a
899 .Dv TELNET EL
900 sequence (see
901 .Ic send
902 .Ic el
903 above)
904 is sent to the remote system.
905 The initial value for the kill character is taken to be
906 the terminal's
907 .Ic kill
908 character.
909 .It Ic lnext
910 If
911 .Nm
912 is operating in
913 .Dv LINEMODE
914 or \*(Lqold line by line\*(Lq mode, then this character is taken to
915 be the terminal's
916 .Ic lnext
917 character.
918 The initial value for the lnext character is taken to be
919 the terminal's
920 .Ic lnext
921 character.
922 .It Ic quit
923 If
924 .Nm
925 is in
926 .Ic localchars
927 mode (see
928 .Ic toggle
929 .Ic localchars
930 below)
931 and the
932 .Ic quit
933 character is typed, a
934 .Dv TELNET BRK
935 sequence (see
936 .Ic send
937 .Ic brk
938 above)
939 is sent to the remote host.
940 The initial value for the quit character is taken to be
941 the terminal's
942 .Ic quit
943 character.
944 .It Ic reprint
945 If
946 .Nm
947 is operating in
948 .Dv LINEMODE
949 or \*(Lqold line by line\*(Lq mode, then this character is taken to
950 be the terminal's
951 .Ic reprint
952 character.
953 The initial value for the reprint character is taken to be
954 the terminal's
955 .Ic reprint
956 character.
957 .It Ic rlogin
958 This is the rlogin escape character.
959 If set, the normal
960 .Tn TELNET
961 escape character is ignored unless it is
962 preceded by this character at the beginning of a line.
963 This character, at the beginning of a line followed by
964 a "." closes the connection; when followed by a ^Z it
965 suspends the
966 .Nm
967 command.
968 The initial state is to
969 disable the rlogin escape character.
970 .It Ic start
971 If the
972 .Dv TELNET TOGGLE-FLOW-CONTROL
973 option has been enabled,
974 then this character is taken to
975 be the terminal's
976 .Ic start
977 character.
978 The initial value for the start character is taken to be
979 the terminal's
980 .Ic start
981 character.
982 .It Ic stop
983 If the
984 .Dv TELNET TOGGLE-FLOW-CONTROL
985 option has been enabled,
986 then this character is taken to
987 be the terminal's
988 .Ic stop
989 character.
990 The initial value for the stop character is taken to be
991 the terminal's
992 .Ic stop
993 character.
994 .It Ic susp
995 If
996 .Nm
997 is in
998 .Ic localchars
999 mode, or
1000 .Dv LINEMODE
1001 is enabled, and the
1002 .Ic suspend
1003 character is typed, a
1004 .Dv TELNET SUSP
1005 sequence (see
1006 .Ic send
1007 .Ic susp
1008 above)
1009 is sent to the remote host.
1010 The initial value for the suspend character is taken to be
1011 the terminal's
1012 .Ic suspend
1013 character.
1014 .It Ic tracefile
1015 This is the file to which the output, caused by
1016 .Ic netdata
1017 or
1018 .Ic option
1019 tracing being
1020 .Dv TRUE ,
1021 will be written.
1022 If it is set to
1023 .Dq Fl ,
1024 then tracing information will be written to standard output (the default).
1025 .It Ic worderase
1026 If
1027 .Nm
1028 is operating in
1029 .Dv LINEMODE
1030 or \*(Lqold line by line\*(Lq mode, then this character is taken to
1031 be the terminal's
1032 .Ic worderase
1033 character.
1034 The initial value for the worderase character is taken to be
1035 the terminal's
1036 .Ic worderase
1037 character.
1038 .It Ic \&?
1039 Displays the legal
1040 .Ic set
1041 .Pq Ic unset
1042 commands.
1043 .El
1044 .It Ic slc Ar state
1045 The
1046 .Ic slc
1047 command (Set Local Characters) is used to set
1048 or change the state of the special
1049 characters when the
1050 .Dv TELNET LINEMODE
1051 option has
1052 been enabled.
1053 Special characters are characters that get
1054 mapped to
1055 .Tn TELNET
1056 commands sequences (like
1057 .Ic ip
1058 or
1059 .Ic quit )
1060 or line editing characters (like
1061 .Ic erase
1062 and
1063 .Ic kill ) .
1064 By default, the local special characters are exported.
1065 .Bl -tag -width Fl
1066 .It Ic check
1067 Verify the current settings for the current special characters.
1068 The remote side is requested to send all the current special
1069 character settings, and if there are any discrepancies with
1070 the local side, the local side will switch to the remote value.
1071 .It Ic export
1072 Switch to the local defaults for the special characters.
1073 The
1074 local default characters are those of the local terminal at
1075 the time when
1076 .Nm
1077 was started.
1078 .It Ic import
1079 Switch to the remote defaults for the special characters.
1080 The remote default characters are those of the remote system
1081 at the time when the
1082 .Tn TELNET
1083 connection was established.
1084 .It Ic \&?
1085 Prints out help information for the
1086 .Ic slc
1087 command.
1088 .El
1089 .It Ic status
1090 Show the current status of
1091 .Nm .
1092 This includes the peer one is connected to, as well
1093 as the current mode.
1094 .It Ic toggle Ar arguments ...
1095 Toggle (between
1096 .Dv TRUE
1097 and
1098 .Dv FALSE )
1099 various flags that control how
1100 .Nm
1101 responds to events.
1102 These flags may be set explicitly to
1103 .Dv TRUE
1104 or
1105 .Dv FALSE
1106 using the
1107 .Ic set
1108 and
1109 .Ic unset
1110 commands listed above.
1111 More than one argument may be specified.
1112 The state of these flags may be interrogated with the
1113 .Ic display
1114 command.
1115 Valid arguments are:
1116 .Bl -tag -width Ar
1117 .It Ic authdebug
1118 Turns on debugging information for the authentication code.
1119 .It Ic autoflush
1120 If
1121 .Ic autoflush
1122 and
1123 .Ic localchars
1124 are both
1125 .Dv TRUE ,
1126 then when the
1127 .Ic ao ,
1128 or
1129 .Ic quit
1130 characters are recognized (and transformed into
1131 .Tn TELNET
1132 sequences; see
1133 .Ic set
1134 above for details),
1135 .Nm
1136 refuses to display any data on the user's terminal
1137 until the remote system acknowledges (via a
1138 .Dv TELNET TIMING MARK
1139 option)
1140 that it has processed those
1141 .Tn TELNET
1142 sequences.
1143 The initial value for this toggle is
1144 .Dv TRUE
1145 if the terminal user had not
1146 done an "stty noflsh", otherwise
1147 .Dv FALSE
1148 (see
1149 .Xr stty 1 ) .
1150 .It Ic autodecrypt
1151 When the
1152 .Dv TELNET ENCRYPT
1153 option is negotiated, by
1154 default the actual encryption (decryption) of the data
1155 stream does not start automatically.
1156 The autoencrypt
1157 (autodecrypt) command states that encryption of the
1158 output (input) stream should be enabled as soon as
1159 possible.
1160 .Pp
1161 Note: Because of export controls, the
1162 .Dv TELNET ENCRYPT
1163 option is not supported outside the United States and Canada.
1164 .It Ic autologin
1165 If the remote side supports the
1166 .Dv TELNET AUTHENTICATION
1167 option
1168 .Tn TELNET
1169 attempts to use it to perform automatic authentication.
1170 If the
1171 .Dv AUTHENTICATION
1172 option is not supported, the user's login
1173 name are propagated through the
1174 .Dv TELNET ENVIRON
1175 option.
1176 This command is the same as specifying the
1177 .Fl a
1178 option on the
1179 .Ic open
1180 command.
1181 .It Ic autosynch
1182 If
1183 .Ic autosynch
1184 and
1185 .Ic localchars
1186 are both
1187 .Dv TRUE ,
1188 then when either the
1189 .Ic intr
1190 or
1191 .Ic quit
1192 characters is typed (see
1193 .Ic set
1194 above for descriptions of the
1195 .Ic intr
1196 and
1197 .Ic quit
1198 characters), the resulting
1199 .Tn TELNET
1200 sequence sent is followed by the
1201 .Dv TELNET SYNCH
1202 sequence.
1203 This procedure
1204 .Ic should
1205 cause the remote system to begin throwing away all previously
1206 typed input until both of the
1207 .Tn TELNET
1208 sequences have been read and acted upon.
1209 The initial value of this toggle is
1210 .Dv FALSE .
1211 .It Ic binary
1212 Enable or disable the
1213 .Dv TELNET BINARY
1214 option on both input and output.
1215 .It Ic inbinary
1216 Enable or disable the
1217 .Dv TELNET BINARY
1218 option on input.
1219 .It Ic outbinary
1220 Enable or disable the
1221 .Dv TELNET BINARY
1222 option on output.
1223 .It Ic crlf
1224 If this is
1225 .Dv TRUE ,
1226 then carriage returns will be sent as
1227 .Li \*[Lt]CR\*[Gt]\*[Lt]LF\*[Gt] .
1228 If this is
1229 .Dv FALSE ,
1230 then carriage returns will be send as
1231 .Li \*[Lt]CR\*[Gt]\*[Lt]NUL\*[Gt] .
1232 The initial value for this toggle is
1233 .Dv FALSE .
1234 .It Ic crmod
1235 Toggle carriage return mode.
1236 When this mode is enabled, most carriage return characters received from
1237 the remote host will be mapped into a carriage return followed by
1238 a line feed.
1239 This mode does not affect those characters typed by the user, only
1240 those received from the remote host.
1241 This mode is not very useful unless the remote host
1242 only sends carriage return, but never line feed.
1243 The initial value for this toggle is
1244 .Dv FALSE .
1245 .It Ic debug
1246 Toggles socket level debugging (useful only to the
1247 .Ic super user ) .
1248 The initial value for this toggle is
1249 .Dv FALSE .
1250 .It Ic encdebug
1251 Turns on debugging information for the encryption code.
1252 .It Ic localchars
1253 If this is
1254 .Dv TRUE ,
1255 then the
1256 .Ic flush ,
1257 .Ic interrupt ,
1258 .Ic quit ,
1259 .Ic erase ,
1260 and
1261 .Ic kill
1262 characters (see
1263 .Ic set
1264 above) are recognized locally, and transformed into (hopefully) appropriate
1265 .Tn TELNET
1266 control sequences
1267 (respectively
1268 .Ic ao ,
1269 .Ic ip ,
1270 .Ic brk ,
1271 .Ic ec ,
1272 and
1273 .Ic el ;
1274 see
1275 .Ic send
1276 above).
1277 The initial value for this toggle is
1278 .Dv TRUE
1279 in \*(Lqold line by line\*(Rq mode,
1280 and
1281 .Dv FALSE
1282 in \*(Lqcharacter at a time\*(Rq mode.
1283 When the
1284 .Dv LINEMODE
1285 option is enabled, the value of
1286 .Ic localchars
1287 is ignored, and assumed to always be
1288 .Dv TRUE .
1289 If
1290 .Dv LINEMODE
1291 has ever been enabled, then
1292 .Ic quit
1293 is sent as
1294 .Ic abort ,
1295 and
1296 .Ic eof and
1297 .Ic suspend
1298 are sent as
1299 .Ic eof and
1300 .Ic susp
1301 (see
1302 .Ic send
1303 above).
1304 .It Ic netdata
1305 Toggles the display of all network data (in hexadecimal format).
1306 The initial value for this toggle is
1307 .Dv FALSE .
1308 .It Ic options
1309 Toggles the display of some internal
1310 .Nm
1311 protocol processing (having to do with
1312 .Tn TELNET
1313 options).
1314 The initial value for this toggle is
1315 .Dv FALSE .
1316 .It Ic prettydump
1317 When the
1318 .Ic netdata
1319 toggle is enabled, if
1320 .Ic prettydump
1321 is enabled the output from the
1322 .Ic netdata
1323 command will be formatted in a more user readable format.
1324 Spaces are put between each character in the output, and the
1325 beginning of any
1326 .Tn TELNET
1327 escape sequence is preceded by a '*' to aid in locating them.
1328 .It Ic skiprc
1329 When the skiprc toggle is
1330 .Dv TRUE ,
1331 .Tn TELNET
1332 skips the reading of the
1333 .Pa \&.telnetrc
1334 file in the users home
1335 directory when connections are opened.
1336 The initial
1337 value for this toggle is
1338 .Dv FALSE .
1339 .It Ic termdata
1340 Toggles the display of all terminal data (in hexadecimal format).
1341 The initial value for this toggle is
1342 .Dv FALSE .
1343 .It Ic verbose_encrypt
1344 When the
1345 .Ic verbose_encrypt
1346 toggle is
1347 .Dv TRUE ,
1348 .Nm
1349 prints out a message each time encryption is enabled or
1350 disabled.
1351 The initial value for this toggle is
1352 .Dv FALSE .
1353 Note: Because of export controls, data encryption
1354 is not supported outside of the United States and Canada.
1355 .It Ic \&?
1356 Displays the legal
1357 .Ic toggle
1358 commands.
1359 .El
1360 .It Ic z
1361 Suspend
1362 .Nm .
1363 This command only works when the user is using the
1364 .Xr csh 1 .
1365 .It Ic \&! Op Ar command
1366 Execute a single command in a subshell on the local
1367 system.
1368 If
1369 .Ar command
1370 is omitted, then an interactive
1371 subshell is invoked.
1372 .It Ic \&? Op Ar command
1373 Get help.
1374 With no arguments,
1375 .Nm
1376 prints a help summary.
1377 If a command is specified,
1378 .Nm
1379 will print the help information for just that command.
1380 .El
1381 .Sh ENVIRONMENT
1382 .Nm
1383 uses at least the
1384 .Ev HOME ,
1385 .Ev SHELL ,
1386 .Ev DISPLAY ,
1387 and
1388 .Ev TERM
1389 environment variables.
1390 Other environment variables may be propagated
1391 to the other side via the
1392 .Dv TELNET ENVIRON
1393 option.
1394 .Sh FILES
1395 .Bl -tag -width ~/.telnetrc -compact
1396 .It Pa ~/.telnetrc
1397 user customized telnet startup values
1398 .El
1399 .Sh HISTORY
1400 The
1401 .Nm
1402 command appeared in
1403 .Bx 4.2 .
1404 IPsec support was added by WIDE/KAME project, in 1999.
1405 .Sh NOTES
1406 On some remote systems, echo has to be turned off manually when in
1407 \*(Lqold line by line\*(Rq mode.
1408 .Pp
1409 In \*(Lqold line by line\*(Rq mode or
1410 .Dv LINEMODE
1411 the terminal's
1412 .Ic eof
1413 character is only recognized (and sent to the remote system)
1414 when it is the first character on a line.