| blob | beab2801951bb73b5f2975ffd6beb8958008ba6a |
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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 4
43 .Op Fl 6
44 .Op Fl 8
45 .Op Fl E
46 .Op Fl F
47 .Op Fl K
48 .Op Fl L
49 .Op Fl N
50 .Bk -words
51 .Op Fl S Ar tos
52 .Ek
53 .Bk -words
54 .Op Fl X Ar authtype
55 .Ek
56 .Op Fl a
57 .Op Fl c
58 .Op Fl d
59 .Bk -words
60 .Op Fl e Ar escapechar
61 .Ek
62 .Op Fl f
63 .Bk -words
64 .Op Fl k Ar realm
65 .Ek
66 .Bk -words
67 .Op Fl l Ar user
68 .Ek
69 .Bk -words
70 .Op Fl n Ar tracefile
71 .Ek
72 .Bk -words
73 .Op Fl P Ar policy
74 .Ek
75 .Op Fl r
76 .Op Fl x
77 .Oo
78 .Ar host
79 .Op Ar port
80 .Oc
81 .Sh DESCRIPTION
82 The
83 .Nm
84 command
85 is used to communicate with another host using the
86 .Tn TELNET
87 protocol.
88 If
89 .Nm
90 is invoked without the
91 .Ar host
92 argument, it enters command mode,
93 indicated by its prompt
94 .Pq Nm telnet\&\*[Gt] .
95 In this mode, it accepts and executes the commands listed below.
96 If it is invoked with arguments, it performs an
97 .Ic open
98 command with those arguments.
99 .Pp
100 Options:
101 .Bl -tag -width indent
102 .It Fl 4
103 Forces
104 .Nm
105 to use IPv4 addresses only.
106 .It Fl 6
107 Forces
108 .Nm
109 to use IPv6 addresses only.
110 .It Fl 8
111 Specifies an 8-bit data path.
112 This causes an attempt to
113 negotiate the
114 .Dv TELNET BINARY
115 option on both input and output.
116 .It Fl E
117 Stops any character from being recognized as an escape character.
118 .It Fl F
119 If Kerberos V5 authentication is being used, the
120 .Fl F
121 option allows the local credentials to be forwarded
122 to the remote system, including any credentials that
123 have already been forwarded into the local environment.
124 .It Fl K
125 Specifies no automatic login to the remote system.
126 .It Fl L
127 Specifies an 8-bit data path on output.
128 This causes the
129 BINARY option to be negotiated on output.
130 .It Fl N
131 Numeric host address.
132 No attempt will be made to look up
133 symbolic names for host addresses.
134 .It Fl S Ar tos
135 Sets the IP type-of-service (TOS) option for the telnet
136 connection to the value
137 .Ar tos ,
138 which can be a numeric TOS value
139 or, on systems that support it, a symbolic
140 TOS name found in the /etc/iptos file.
141 .It Fl X Ar atype
142 Disables the
143 .Ar atype
144 type of authentication.
145 .It Fl a
146 Attempt automatic login.
147 Currently, this sends the user name via the
148 .Ev USER
149 variable
150 of the
151 .Ev ENVIRON
152 option if supported by the remote system.
153 The name used is that of the current user as returned by
154 .Xr getlogin 2
155 if it agrees with the current user ID,
156 otherwise it is the name associated with the user ID.
157 .It Fl c
158 Disables the reading of the user's
159 .Pa \&.telnetrc
160 file.
161 (See the
162 .Ic toggle skiprc
163 command on this man page.)
164 .It Fl d
165 Sets the initial value of the
166 .Ic debug
167 toggle to
168 .Dv TRUE .
169 .It Fl e Ar escape char
170 Sets the initial
171 .Nm
172 escape character to
173 .Ar escape char .
174 If
175 .Ar escape char
176 is omitted, then
177 there will be no escape character.
178 .It Fl f
179 If Kerberos V5 authentication is being used, the
180 .Fl f
181 option allows the local credentials to be forwarded to the remote system.
182 .It Fl k Ar realm
183 If Kerberos authentication is being used, the
184 .Fl k
185 option requests that telnet obtain tickets for the remote host in
186 realm
187 .Ar realm
188 instead of the remote host's realm, as determined by
189 .Xr krb_realmofhost 3 .
190 .It Fl l Ar user
191 When connecting to the remote system, if the remote system
192 understands the
193 .Ev ENVIRON
194 option, then
195 .Ar user
196 will be sent to the remote system as the value for the variable USER.
197 This option implies the
198 .Fl a
199 option.
200 This option may also be used with the
201 .Ic open
202 command.
203 .It Fl n Ar tracefile
204 Opens
205 .Ar tracefile
206 for recording trace information.
207 See the
208 .Ic set tracefile
209 command below.
210 .It Fl P Ar policy
211 Use IPsec policy specification string
212 .Ar policy ,
213 for the connections.
214 See
215 .Xr ipsec_set_policy 3
216 for details.
217 .It Fl r
218 Specifies a user interface similar to
219 .Xr rlogin 1 .
220 In this
221 mode, the escape character is set to the tilde (~) character,
222 unless modified by the
223 .Fl e
224 option.
225 .It Fl x
226 Turns on encryption of the data stream if possible.
227 This
228 option is not available outside of the United States and
229 Canada.
230 .It Ar host
231 Indicates the official name, an alias, or the Internet address
232 of a remote host.
233 .It Ar port
234 Indicates a port number (address of an application).
235 If a number is
236 not specified, the default
237 .Nm
238 port is used.
239 .El
240 .Pp
241 When in rlogin mode, a line of the form ~.
242 disconnects from the
243 remote host; ~ is the telnet escape character.
244 Similarly, the line ~^Z suspends the telnet session.
245 The line ~^] escapes to the normal telnet escape prompt.
246 .Pp
247 Once a connection has been opened,
248 .Nm
249 will attempt to enable the
250 .Dv TELNET LINEMODE
251 option.
252 If this fails, then
253 .Nm
254 will revert to one of two input modes:
255 either \*(Lqcharacter at a time\*(Rq
256 or \*(Lqold line by line\*(Rq
257 depending on what the remote system supports.
258 .Pp
259 When
260 .Dv LINEMODE
261 is enabled, character processing is done on the
262 local system, under the control of the remote system.
263 When input
264 editing or character echoing is to be disabled, the remote system
265 will relay that information.
266 The remote system will also relay
267 changes to any special characters that happen on the remote
268 system, so that they can take effect on the local system.
269 .Pp
270 In \*(Lqcharacter at a time\*(Rq mode, most
271 text typed is immediately sent to the remote host for processing.
272 .Pp
273 In \*(Lqold line by line\*(Rq mode, all text is echoed locally,
274 and (normally) only completed lines are sent to the remote host.
275 The \*(Lqlocal echo character\*(Rq (initially \*(Lq^E\*(Rq) may be used
276 to turn off and on the local echo
277 (this would mostly be used to enter passwords
278 without the password being echoed).
279 .Pp
280 If the
281 .Dv LINEMODE
282 option is enabled, or if the
283 .Ic localchars
284 toggle is
285 .Dv TRUE
286 (the default for \*(Lqold line by line\*(Lq; see below),
287 the user's
288 .Ic quit ,
289 .Ic intr ,
290 and
291 .Ic flush
292 characters are trapped locally, and sent as
293 .Tn TELNET
294 protocol sequences to the remote side.
295 If
296 .Dv LINEMODE
297 has ever been enabled, then the user's
298 .Ic susp
299 and
300 .Ic eof
301 are also sent as
302 .Tn TELNET
303 protocol sequences,
304 and
305 .Ic quit
306 is sent as a
307 .Dv TELNET ABORT
308 instead of
309 .Dv BREAK .
310 There are options (see
311 .Ic toggle
312 .Ic autoflush
313 and
314 .Ic toggle
315 .Ic autosynch
316 below)
317 which cause this action to flush subsequent output to the terminal
318 (until the remote host acknowledges the
319 .Tn TELNET
320 sequence) and flush previous terminal input
321 (in the case of
322 .Ic quit
323 and
324 .Ic intr ) .
325 .Pp
326 While connected to a remote host,
327 .Nm
328 command mode may be entered by typing the
329 .Nm
330 \*(Lqescape character\*(Rq (initially \*(Lq^]\*(Rq).
331 When in command mode, the normal terminal editing conventions are available.
332 .Pp
333 The following
334 .Nm
335 commands are available.
336 Only enough of each command to uniquely identify it need be typed
337 (this is also true for arguments to the
338 .Ic mode ,
339 .Ic set ,
340 .Ic toggle ,
341 .Ic unset ,
342 .Ic slc ,
343 .Ic environ ,
344 and
345 .Ic display
346 commands).
347 .Pp
348 .Bl -tag -width "mode type"
349 .It Ic auth Ar argument ...
350 The auth command manipulates the information sent through the
351 .Dv TELNET AUTHENTICATE
352 option.
353 Valid arguments for the
354 auth command are as follows:
355 .Bl -tag -width "disable type"
356 .It Ic disable Ar type
357 Disables the specified type of authentication.
358 To obtain a list of available types, use the
359 .Ic auth disable \&?
360 command.
361 .It Ic enable Ar type
362 Enables the specified type of authentication.
363 To obtain a list of available types, use the
364 .Ic auth enable \&?
365 command.
366 .It Ic status
367 Lists the current status of the various types of
368 authentication.
369 .El
370 .It Ic close
371 Close a
372 .Tn TELNET
373 session and return to command mode.
374 .It Ic display Ar argument ...
375 Displays all, or some, of the
376 .Ic set
377 and
378 .Ic toggle
379 values (see below).
380 .It Ic encrypt Ar argument ...
381 The encrypt command manipulates the information sent through the
382 .Dv TELNET ENCRYPT
383 option.
384 .Pp
385 Note: Because of export controls, the
386 .Dv TELNET ENCRYPT
387 option is not supported outside of the United States and Canada.
388 .Pp
389 Valid arguments for the encrypt command are:
390 .Bl -tag -width Ar
391 .It Ic disable Ar type Ic [input|output]
392 Disables the specified type of encryption.
393 If you omit the input and output, both input and output
394 are disabled.
395 To obtain a list of available types, use the
396 .Ic encrypt disable \&?
397 command.
398 .It Ic enable Ar type Ic [input|output]
399 Enables the specified type of encryption.
400 If you omit input and output, both input and output are
401 enabled.
402 To obtain a list of available types, use the
403 .Ic encrypt enable \&?
404 command.
405 .It Ic input
406 This is the same as the
407 .Ic encrypt start input
408 command.
409 .It Ic -input
410 This is the same as the
411 .Ic encrypt stop input
412 command.
413 .It Ic output
414 This is the same as the
415 .Ic encrypt start output
416 command.
417 .It Ic -output
418 This is the same as the
419 .Ic encrypt stop output
420 command.
421 .It Ic start Ic [input|output]
422 Attempts to start encryption.
423 If you omit
424 .Ic input
425 and
426 .Ic output ,
427 both input and output are enabled.
428 To obtain a list of available types, use the
429 .Ic encrypt enable \&?
430 command.
431 .It Ic status
432 Lists the current status of encryption.
433 .It Ic stop Ic [input|output]
434 Stops encryption.
435 If you omit input and output,
436 encryption is on both input and output.
437 .It Ic type Ar type
438 Sets the default type of encryption to be used
439 with later
440 .Ic encrypt start
441 or
442 .Ic encrypt stop
443 commands.
444 .El
445 .It Ic environ Ar arguments ...
446 The
447 .Ic environ
448 command is used to manipulate the
449 variables that may be sent through the
450 .Dv TELNET ENVIRON
451 option.
452 The initial set of variables is taken from the users
453 environment, with only the
454 .Ev DISPLAY
455 and
456 .Ev PRINTER
457 variables being exported by default.
458 The
459 .Ev USER
460 variable is also exported if the
461 .Fl a
462 or
463 .Fl l
464 options are used.
465 .Pp
466 Valid arguments for the
467 .Ic environ
468 command are:
469 .Bl -tag -width Fl
470 .It Ic define Ar variable value
471 Define the variable
472 .Ar variable
473 to have a value of
474 .Ar value .
475 Any variables defined by this command are automatically exported.
476 The
477 .Ar value
478 may be enclosed in single or double quotes so
479 that tabs and spaces may be included.
480 .It Ic undefine Ar variable
481 Remove
482 .Ar variable
483 from the list of environment variables.
484 .It Ic export Ar variable
485 Mark the variable
486 .Ar variable
487 to be exported to the remote side.
488 .It Ic unexport Ar variable
489 Mark the variable
490 .Ar variable
491 to not be exported unless
492 explicitly asked for by the remote side.
493 .It Ic list
494 List the current set of environment variables.
495 Those marked with a
496 .Cm *
497 will be sent automatically,
498 other variables will only be sent if explicitly requested.
499 .It Ic \&?
500 Prints out help information for the
501 .Ic environ
502 command.
503 .El
504 .It Ic logout
505 Sends the
506 .Dv TELNET LOGOUT
507 option to the remote side.
508 This command is similar to a
509 .Ic close
510 command; however, if the remote side does not support the
511 .Dv LOGOUT
512 option, nothing happens.
513 If, however, the remote side does support the
514 .Dv LOGOUT
515 option, this command should cause the remote side to close the
516 .Tn TELNET
517 connection.
518 If the remote side also supports the concept of
519 suspending a user's session for later reattachment,
520 the logout argument indicates that you
521 should terminate the session immediately.
522 .It Ic mode Ar type
523 .Ar Type
524 is one of several options, depending on the state of the
525 .Tn TELNET
526 session.
527 The remote host is asked for permission to go into the requested mode.
528 If the remote host is capable of entering that mode, the requested
529 mode will be entered.
530 .Bl -tag -width Ar
531 .It Ic character
532 Disable the
533 .Dv TELNET LINEMODE
534 option, or, if the remote side does not understand the
535 .Dv LINEMODE
536 option, then enter \*(Lqcharacter at a time\*(Lq mode.
537 .It Ic line
538 Enable the
539 .Dv TELNET LINEMODE
540 option, or, if the remote side does not understand the
541 .Dv LINEMODE
542 option, then attempt to enter \*(Lqold-line-by-line\*(Lq mode.
543 .It Ic isig Pq Ic \-isig
544 Attempt to enable (disable) the
545 .Dv TRAPSIG
546 mode of the
547 .Dv LINEMODE
548 option.
549 This requires that the
550 .Dv LINEMODE
551 option be enabled.
552 .It Ic edit Pq Ic \-edit
553 Attempt to enable (disable) the
554 .Dv EDIT
555 mode of the
556 .Dv LINEMODE
557 option.
558 This requires that the
559 .Dv LINEMODE
560 option be enabled.
561 .It Ic softtabs Pq Ic \-softtabs
562 Attempt to enable (disable) the
563 .Dv SOFT_TAB
564 mode of the
565 .Dv LINEMODE
566 option.
567 This requires that the
568 .Dv LINEMODE
569 option be enabled.
570 .It Ic litecho Pq Ic \-litecho
571 Attempt to enable (disable) the
572 .Dv LIT_ECHO
573 mode of the
574 .Dv LINEMODE
575 option.
576 This requires that the
577 .Dv LINEMODE
578 option be enabled.
579 .It Ic \&?
580 Prints out help information for the
581 .Ic mode
582 command.
583 .El
584 .It Ic open Ar host Oo Fl l Ar user Oc Oo Fl a Oc Oo Oo \&- Oc Ns Ar port Oc
585 Open a connection to the named host.
586 If no port number
587 is specified,
588 .Nm
589 will attempt to contact a
590 .Tn TELNET
591 server at the default port.
592 The host specification may be either a host name (see
593 .Xr hosts 5 )
594 or an Internet address specified in the \*(Lqdot notation\*(Rq (see
595 .Xr inet 3 ) .
596 The
597 .Fl l
598 option may be used to specify the user name
599 to be passed to the remote system via the
600 .Ev ENVIRON
601 option.
602 If a port is specified
603 .Nm
604 omits any automatic initialisation of
605 .Tn TELNET
606 options.
607 When the port number is preceded by a minus sign,
608 the initial option negotiation is done.
609 .Pp
610 After establishing a connection, the file
611 .Pa \&.telnetrc
612 in the
613 user's home directory is read.
614 Lines beginning with a # are
615 comment lines.
616 Blank lines are ignored.
617 Lines that begin
618 without white space are the start of a machine entry.
619 The first thing on such a line is a string identifying the machine
620 that is being connected to.
621 It may be the hostname or numeric address specified as the argument
622 .Ar host ,
623 the canonical name of that string as determined by
624 .Xr getaddrinfo 3 ,
625 or the string
626 .Dq DEFAULT
627 indicating all hosts.
628 The rest of the line, and successive
629 lines that begin with white space are assumed to be
630 .Nm
631 commands and are processed as if they had been typed
632 in manually to the
633 .Nm
634 command prompt.
635 .It Ic quit
636 Close any open
637 .Tn TELNET
638 session and exit
639 .Nm .
640 An end of file (in command mode) will also close a session and exit.
641 .It Ic send Ar arguments
642 Sends one or more special character sequences to the remote host.
643 The following are the arguments which may be specified
644 (more than one argument may be specified at a time):
645 .Pp
646 .Bl -tag -width escape
647 .It Ic abort
648 Sends the
649 .Dv TELNET ABORT
650 (Abort
651 processes)
652 sequence.
653 .It Ic ao
654 Sends the
655 .Dv TELNET AO
656 (Abort Output) sequence, which should cause the remote system to flush
657 all output
658 .Em from
659 the remote system
660 .Em to
661 the user's terminal.
662 .It Ic ayt
663 Sends the
664 .Dv TELNET AYT
665 (Are You There)
666 sequence, to which the remote system may or may not choose to respond.
667 .It Ic brk
668 Sends the
669 .Dv TELNET BRK
670 (Break) sequence, which may have significance to the remote
671 system.
672 .It Ic ec
673 Sends the
674 .Dv TELNET EC
675 (Erase Character)
676 sequence, which should cause the remote system to erase the last character
677 entered.
678 .It Ic el
679 Sends the
680 .Dv TELNET EL
681 (Erase Line)
682 sequence, which should cause the remote system to erase the line currently
683 being entered.
684 .It Ic eof
685 Sends the
686 .Dv TELNET EOF
687 (End Of File)
688 sequence.
689 .It Ic eor
690 Sends the
691 .Dv TELNET EOR
692 (End of Record)
693 sequence.
694 .It Ic escape
695 Sends the current
696 .Nm
697 escape character (initially \*(Lq^\*(Rq).
698 .It Ic ga
699 Sends the
700 .Dv TELNET GA
701 (Go Ahead)
702 sequence, which likely has no significance to the remote system.
703 .It Ic getstatus
704 If the remote side supports the
705 .Dv TELNET STATUS
706 command,
707 .Ic getstatus
708 will send the subnegotiation to request that the server send
709 its current option status.
710 .It Ic ip
711 Sends the
712 .Dv TELNET IP
713 (Interrupt Process) sequence, which should cause the remote
714 system to abort the currently running process.
715 .It Ic nop
716 Sends the
717 .Dv TELNET NOP
718 (No OPeration)
719 sequence.
720 .It Ic susp
721 Sends the
722 .Dv TELNET SUSP
723 (SUSPend process)
724 sequence.
725 .It Ic synch
726 Sends the
727 .Dv TELNET SYNCH
728 sequence.
729 This sequence causes the remote system to discard all previously typed
730 (but not yet read) input.
731 This sequence is sent as
732 .Tn TCP
733 urgent
734 data (and may not work if the remote system is a
735 .Bx 4.2
736 system -- if
737 it doesn't work, a lower case \*(Lqr\*(Rq may be echoed on the terminal).
738 .It Ic do Ar cmd
739 .It Ic dont Ar cmd
740 .It Ic will Ar cmd
741 .It Ic wont Ar cmd
742 Sends the
743 .Dv TELNET DO
744 .Ar cmd
745 sequence.
746 .Ar Cmd
747 can be either a decimal number between 0 and 255,
748 or a symbolic name for a specific
749 .Dv TELNET
750 command.
751 .Ar Cmd
752 can also be either
753 .Ic help
754 or
755 .Ic \&?
756 to print out help information, including
757 a list of known symbolic names.
758 .It Ic \&?
759 Prints out help information for the
760 .Ic send
761 command.
762 .El
763 .It Ic set Ar argument value
764 .It Ic unset Ar argument value
765 The
766 .Ic set
767 command will set any one of a number of
768 .Nm
769 variables to a specific value or to
770 .Dv TRUE .
771 The special value
772 .Ic off
773 turns off the function associated with
774 the variable, this is equivalent to using the
775 .Ic unset
776 command.
777 The
778 .Ic unset
779 command will disable or set to
780 .Dv FALSE
781 any of the specified functions.
782 The values of variables may be interrogated with the
783 .Ic display
784 command.
785 The variables which may be set or unset, but not toggled, are
786 listed here.
787 In addition, any of the variables for the
788 .Ic toggle
789 command may be explicitly set or unset using
790 the
791 .Ic set
792 and
793 .Ic unset
794 commands.
795 .Bl -tag -width escape
796 .It Ic ayt
797 If
798 .Tn TELNET
799 is in localchars mode, or
800 .Dv LINEMODE
801 is enabled, and the status character is typed, a
802 .Dv TELNET AYT
803 sequence (see
804 .Ic send ayt
805 above) is sent to the
806 remote host.
807 The initial value for the "Are You There"
808 character is the terminal's status character.
809 .It Ic echo
810 This is the value (initially \*(Lq^E\*(Rq) which, when in
811 \*(Lqline by line\*(Rq mode, toggles between doing local echoing
812 of entered characters (for normal processing), and suppressing
813 echoing of entered characters (for entering, say, a password).
814 .It Ic eof
815 If
816 .Nm
817 is operating in
818 .Dv LINEMODE
819 or \*(Lqold line by line\*(Rq mode, entering this character
820 as the first character on a line will cause this character to be
821 sent to the remote system.
822 The initial value of the eof character is taken to be the terminal's
823 .Ic eof
824 character.
825 .It Ic erase
826 If
827 .Nm
828 is in
829 .Ic localchars
830 mode (see
831 .Ic toggle
832 .Ic localchars
833 below),
834 .Sy and
835 if
836 .Nm
837 is operating in \*(Lqcharacter at a time\*(Rq mode, then when this
838 character is typed, a
839 .Dv TELNET EC
840 sequence (see
841 .Ic send
842 .Ic ec
843 above)
844 is sent to the remote system.
845 The initial value for the erase character is taken to be
846 the terminal's
847 .Ic erase
848 character.
849 .It Ic escape
850 This is the
851 .Nm
852 escape character (initially \*(Lq^[\*(Rq) which causes entry
853 into
854 .Nm
855 command mode (when connected to a remote system).
856 .It Ic flushoutput
857 If
858 .Nm
859 is in
860 .Ic localchars
861 mode (see
862 .Ic toggle
863 .Ic localchars
864 below)
865 and the
866 .Ic flushoutput
867 character is typed, a
868 .Dv TELNET AO
869 sequence (see
870 .Ic send
871 .Ic ao
872 above)
873 is sent to the remote host.
874 The initial value for the flush character is taken to be
875 the terminal's
876 .Ic flush
877 character.
878 .It Ic forw1
879 .It Ic forw2
880 If
881 .Tn TELNET
882 is operating in
883 .Dv LINEMODE ,
884 these are the
885 characters that, when typed, cause partial lines to be
886 forwarded to the remote system.
887 The initial value for
888 the forwarding characters are taken from the terminal's
889 eol and eol2 characters.
890 .It Ic interrupt
891 If
892 .Nm
893 is in
894 .Ic localchars
895 mode (see
896 .Ic toggle
897 .Ic localchars
898 below)
899 and the
900 .Ic interrupt
901 character is typed, a
902 .Dv TELNET IP
903 sequence (see
904 .Ic send
905 .Ic ip
906 above)
907 is sent to the remote host.
908 The initial value for the interrupt character is taken to be
909 the terminal's
910 .Ic intr
911 character.
912 .It Ic kill
913 If
914 .Nm
915 is in
916 .Ic localchars
917 mode (see
918 .Ic toggle
919 .Ic localchars
920 below),
921 .Ic and
922 if
923 .Nm
924 is operating in \*(Lqcharacter at a time\*(Rq mode, then when this
925 character is typed, a
926 .Dv TELNET EL
927 sequence (see
928 .Ic send
929 .Ic el
930 above)
931 is sent to the remote system.
932 The initial value for the kill character is taken to be
933 the terminal's
934 .Ic kill
935 character.
936 .It Ic lnext
937 If
938 .Nm
939 is operating in
940 .Dv LINEMODE
941 or \*(Lqold line by line\*(Lq mode, then this character is taken to
942 be the terminal's
943 .Ic lnext
944 character.
945 The initial value for the lnext character is taken to be
946 the terminal's
947 .Ic lnext
948 character.
949 .It Ic quit
950 If
951 .Nm
952 is in
953 .Ic localchars
954 mode (see
955 .Ic toggle
956 .Ic localchars
957 below)
958 and the
959 .Ic quit
960 character is typed, a
961 .Dv TELNET BRK
962 sequence (see
963 .Ic send
964 .Ic brk
965 above)
966 is sent to the remote host.
967 The initial value for the quit character is taken to be
968 the terminal's
969 .Ic quit
970 character.
971 .It Ic reprint
972 If
973 .Nm
974 is operating in
975 .Dv LINEMODE
976 or \*(Lqold line by line\*(Lq mode, then this character is taken to
977 be the terminal's
978 .Ic reprint
979 character.
980 The initial value for the reprint character is taken to be
981 the terminal's
982 .Ic reprint
983 character.
984 .It Ic rlogin
985 This is the rlogin escape character.
986 If set, the normal
987 .Tn TELNET
988 escape character is ignored unless it is
989 preceded by this character at the beginning of a line.
990 This character, at the beginning of a line followed by
991 a "." closes the connection; when followed by a ^Z it
992 suspends the
993 .Nm
994 command.
995 The initial state is to
996 disable the rlogin escape character.
997 .It Ic start
998 If the
999 .Dv TELNET TOGGLE-FLOW-CONTROL
1000 option has been enabled,
1001 then this character is taken to
1002 be the terminal's
1003 .Ic start
1004 character.
1005 The initial value for the start character is taken to be
1006 the terminal's
1007 .Ic start
1008 character.
1009 .It Ic stop
1010 If the
1011 .Dv TELNET TOGGLE-FLOW-CONTROL
1012 option has been enabled,
1013 then this character is taken to
1014 be the terminal's
1015 .Ic stop
1016 character.
1017 The initial value for the stop character is taken to be
1018 the terminal's
1019 .Ic stop
1020 character.
1021 .It Ic susp
1022 If
1023 .Nm
1024 is in
1025 .Ic localchars
1026 mode, or
1027 .Dv LINEMODE
1028 is enabled, and the
1029 .Ic suspend
1030 character is typed, a
1031 .Dv TELNET SUSP
1032 sequence (see
1033 .Ic send
1034 .Ic susp
1035 above)
1036 is sent to the remote host.
1037 The initial value for the suspend character is taken to be
1038 the terminal's
1039 .Ic suspend
1040 character.
1041 .It Ic tracefile
1042 This is the file to which the output, caused by
1043 .Ic netdata
1044 or
1045 .Ic option
1046 tracing being
1047 .Dv TRUE ,
1048 will be written.
1049 If it is set to
1050 .Dq Fl ,
1051 then tracing information will be written to standard output (the default).
1052 .It Ic worderase
1053 If
1054 .Nm
1055 is operating in
1056 .Dv LINEMODE
1057 or \*(Lqold line by line\*(Lq mode, then this character is taken to
1058 be the terminal's
1059 .Ic worderase
1060 character.
1061 The initial value for the worderase character is taken to be
1062 the terminal's
1063 .Ic worderase
1064 character.
1065 .It Ic \&?
1066 Displays the legal
1067 .Ic set
1068 .Pq Ic unset
1069 commands.
1070 .El
1071 .It Ic slc Ar state
1072 The
1073 .Ic slc
1074 command (Set Local Characters) is used to set
1075 or change the state of the special
1076 characters when the
1077 .Dv TELNET LINEMODE
1078 option has
1079 been enabled.
1080 Special characters are characters that get
1081 mapped to
1082 .Tn TELNET
1083 commands sequences (like
1084 .Ic ip
1085 or
1086 .Ic quit )
1087 or line editing characters (like
1088 .Ic erase
1089 and
1090 .Ic kill ) .
1091 By default, the local special characters are exported.
1092 .Bl -tag -width Fl
1093 .It Ic check
1094 Verify the current settings for the current special characters.
1095 The remote side is requested to send all the current special
1096 character settings, and if there are any discrepancies with
1097 the local side, the local side will switch to the remote value.
1098 .It Ic export
1099 Switch to the local defaults for the special characters.
1100 The
1101 local default characters are those of the local terminal at
1102 the time when
1103 .Nm
1104 was started.
1105 .It Ic import
1106 Switch to the remote defaults for the special characters.
1107 The remote default characters are those of the remote system
1108 at the time when the
1109 .Tn TELNET
1110 connection was established.
1111 .It Ic \&?
1112 Prints out help information for the
1113 .Ic slc
1114 command.
1115 .El
1116 .It Ic status
1117 Show the current status of
1118 .Nm .
1119 This includes the peer one is connected to, as well
1120 as the current mode.
1121 .It Ic toggle Ar arguments ...
1122 Toggle (between
1123 .Dv TRUE
1124 and
1125 .Dv FALSE )
1126 various flags that control how
1127 .Nm
1128 responds to events.
1129 These flags may be set explicitly to
1130 .Dv TRUE
1131 or
1132 .Dv FALSE
1133 using the
1134 .Ic set
1135 and
1136 .Ic unset
1137 commands listed above.
1138 More than one argument may be specified.
1139 The state of these flags may be interrogated with the
1140 .Ic display
1141 command.
1142 Valid arguments are:
1143 .Bl -tag -width Ar
1144 .It Ic authdebug
1145 Turns on debugging information for the authentication code.
1146 .It Ic autoflush
1147 If
1148 .Ic autoflush
1149 and
1150 .Ic localchars
1151 are both
1152 .Dv TRUE ,
1153 then when the
1154 .Ic ao ,
1155 or
1156 .Ic quit
1157 characters are recognized (and transformed into
1158 .Tn TELNET
1159 sequences; see
1160 .Ic set
1161 above for details),
1162 .Nm
1163 refuses to display any data on the user's terminal
1164 until the remote system acknowledges (via a
1165 .Dv TELNET TIMING MARK
1166 option)
1167 that it has processed those
1168 .Tn TELNET
1169 sequences.
1170 The initial value for this toggle is
1171 .Dv TRUE
1172 if the terminal user had not
1173 done an "stty noflsh", otherwise
1174 .Dv FALSE
1175 (see
1176 .Xr stty 1 ) .
1177 .It Ic autodecrypt
1178 When the
1179 .Dv TELNET ENCRYPT
1180 option is negotiated, by
1181 default the actual encryption (decryption) of the data
1182 stream does not start automatically.
1183 The autoencrypt
1184 (autodecrypt) command states that encryption of the
1185 output (input) stream should be enabled as soon as
1186 possible.
1187 .Pp
1188 Note: Because of export controls, the
1189 .Dv TELNET ENCRYPT
1190 option is not supported outside the United States and Canada.
1191 .It Ic autologin
1192 If the remote side supports the
1193 .Dv TELNET AUTHENTICATION
1194 option
1195 .Tn TELNET
1196 attempts to use it to perform automatic authentication.
1197 If the
1198 .Dv AUTHENTICATION
1199 option is not supported, the user's login
1200 name are propagated through the
1201 .Dv TELNET ENVIRON
1202 option.
1203 This command is the same as specifying the
1204 .Fl a
1205 option on the
1206 .Ic open
1207 command.
1208 .It Ic autosynch
1209 If
1210 .Ic autosynch
1211 and
1212 .Ic localchars
1213 are both
1214 .Dv TRUE ,
1215 then when either the
1216 .Ic intr
1217 or
1218 .Ic quit
1219 characters is typed (see
1220 .Ic set
1221 above for descriptions of the
1222 .Ic intr
1223 and
1224 .Ic quit
1225 characters), the resulting
1226 .Tn TELNET
1227 sequence sent is followed by the
1228 .Dv TELNET SYNCH
1229 sequence.
1230 This procedure
1231 .Ic should
1232 cause the remote system to begin throwing away all previously
1233 typed input until both of the
1234 .Tn TELNET
1235 sequences have been read and acted upon.
1236 The initial value of this toggle is
1237 .Dv FALSE .
1238 .It Ic binary
1239 Enable or disable the
1240 .Dv TELNET BINARY
1241 option on both input and output.
1242 .It Ic inbinary
1243 Enable or disable the
1244 .Dv TELNET BINARY
1245 option on input.
1246 .It Ic outbinary
1247 Enable or disable the
1248 .Dv TELNET BINARY
1249 option on output.
1250 .It Ic crlf
1251 If this is
1252 .Dv TRUE ,
1253 then carriage returns will be sent as
1254 .Li \*[Lt]CR\*[Gt]\*[Lt]LF\*[Gt] .
1255 If this is
1256 .Dv FALSE ,
1257 then carriage returns will be send as
1258 .Li \*[Lt]CR\*[Gt]\*[Lt]NUL\*[Gt] .
1259 The initial value for this toggle is
1260 .Dv FALSE .
1261 .It Ic crmod
1262 Toggle carriage return mode.
1263 When this mode is enabled, most carriage return characters received from
1264 the remote host will be mapped into a carriage return followed by
1265 a line feed.
1266 This mode does not affect those characters typed by the user, only
1267 those received from the remote host.
1268 This mode is not very useful unless the remote host
1269 only sends carriage return, but never line feed.
1270 The initial value for this toggle is
1271 .Dv FALSE .
1272 .It Ic debug
1273 Toggles socket level debugging (useful only to the
1274 .Ic super user ) .
1275 The initial value for this toggle is
1276 .Dv FALSE .
1277 .It Ic encdebug
1278 Turns on debugging information for the encryption code.
1279 .It Ic localchars
1280 If this is
1281 .Dv TRUE ,
1282 then the
1283 .Ic flush ,
1284 .Ic interrupt ,
1285 .Ic quit ,
1286 .Ic erase ,
1287 and
1288 .Ic kill
1289 characters (see
1290 .Ic set
1291 above) are recognized locally, and transformed into (hopefully) appropriate
1292 .Tn TELNET
1293 control sequences
1294 (respectively
1295 .Ic ao ,
1296 .Ic ip ,
1297 .Ic brk ,
1298 .Ic ec ,
1299 and
1300 .Ic el ;
1301 see
1302 .Ic send
1303 above).
1304 The initial value for this toggle is
1305 .Dv TRUE
1306 in \*(Lqold line by line\*(Rq mode,
1307 and
1308 .Dv FALSE
1309 in \*(Lqcharacter at a time\*(Rq mode.
1310 When the
1311 .Dv LINEMODE
1312 option is enabled, the value of
1313 .Ic localchars
1314 is ignored, and assumed to always be
1315 .Dv TRUE .
1316 If
1317 .Dv LINEMODE
1318 has ever been enabled, then
1319 .Ic quit
1320 is sent as
1321 .Ic abort ,
1322 and
1323 .Ic eof and
1324 .Ic suspend
1325 are sent as
1326 .Ic eof and
1327 .Ic susp
1328 (see
1329 .Ic send
1330 above).
1331 .It Ic netdata
1332 Toggles the display of all network data (in hexadecimal format).
1333 The initial value for this toggle is
1334 .Dv FALSE .
1335 .It Ic options
1336 Toggles the display of some internal
1337 .Nm
1338 protocol processing (having to do with
1339 .Tn TELNET
1340 options).
1341 The initial value for this toggle is
1342 .Dv FALSE .
1343 .It Ic prettydump
1344 When the
1345 .Ic netdata
1346 toggle is enabled, if
1347 .Ic prettydump
1348 is enabled the output from the
1349 .Ic netdata
1350 command will be formatted in a more user readable format.
1351 Spaces are put between each character in the output, and the
1352 beginning of any
1353 .Tn TELNET
1354 escape sequence is preceded by a '*' to aid in locating them.
1355 .It Ic skiprc
1356 When the skiprc toggle is
1357 .Dv TRUE ,
1358 .Tn TELNET
1359 skips the reading of the
1360 .Pa \&.telnetrc
1361 file in the users home
1362 directory when connections are opened.
1363 The initial
1364 value for this toggle is
1365 .Dv FALSE .
1366 .It Ic termdata
1367 Toggles the display of all terminal data (in hexadecimal format).
1368 The initial value for this toggle is
1369 .Dv FALSE .
1370 .It Ic verbose_encrypt
1371 When the
1372 .Ic verbose_encrypt
1373 toggle is
1374 .Dv TRUE ,
1375 .Nm
1376 prints out a message each time encryption is enabled or
1377 disabled.
1378 The initial value for this toggle is
1379 .Dv FALSE .
1380 Note: Because of export controls, data encryption
1381 is not supported outside of the United States and Canada.
1382 .It Ic \&?
1383 Displays the legal
1384 .Ic toggle
1385 commands.
1386 .El
1387 .It Ic z
1388 Suspend
1389 .Nm .
1390 This command only works when the user is using the
1391 .Xr csh 1 .
1392 .It Ic \&! Op Ar command
1393 Execute a single command in a subshell on the local
1394 system.
1395 If
1396 .Ar command
1397 is omitted, then an interactive
1398 subshell is invoked.
1399 .It Ic \&? Op Ar command
1400 Get help.
1401 With no arguments,
1402 .Nm
1403 prints a help summary.
1404 If a command is specified,
1405 .Nm
1406 will print the help information for just that command.
1407 .El
1408 .Sh ENVIRONMENT
1409 .Nm
1410 uses at least the
1411 .Ev HOME ,
1412 .Ev SHELL ,
1413 .Ev DISPLAY ,
1414 and
1415 .Ev TERM
1416 environment variables.
1417 Other environment variables may be propagated
1418 to the other side via the
1419 .Dv TELNET ENVIRON
1420 option.
1421 .Sh FILES
1422 .Bl -tag -width ~/.telnetrc -compact
1423 .It Pa ~/.telnetrc
1424 user customized telnet startup values
1425 .El
1426 .Sh HISTORY
1427 The
1428 .Nm
1429 command appeared in
1430 .Bx 4.2 .
1431 IPsec support was added by WIDE/KAME project, in 1999.
1432 .Sh NOTES
1433 On some remote systems, echo has to be turned off manually when in
1434 \*(Lqold line by line\*(Rq mode.
1435 .Pp
1436 In \*(Lqold line by line\*(Rq mode or
1437 .Dv LINEMODE
1438 the terminal's
1439 .Ic eof
1440 character is only recognized (and sent to the remote system)
1441 when it is the first character on a line.