Annotation of src/usr.bin/telnet/telnet.1, Revision 1.9
1.9 ! deraadt 1: .\" $OpenBSD: telnet.1,v 1.8 1997/11/11 18:15:28 deraadt Exp $
1.2 niklas 2: .\" $NetBSD: telnet.1,v 1.5 1996/02/28 21:04:12 thorpej Exp $
3: .\"
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35: .\" from: @(#)telnet.1 8.4 (Berkeley) 2/3/94
36: .\"
37: .Dd February 3, 1994
38: .Dt TELNET 1
39: .Os BSD 4.2
40: .Sh NAME
41: .Nm telnet
42: .Nd user interface to the
43: .Tn TELNET
44: protocol
45: .Sh SYNOPSIS
46: .Nm telnet
47: .Op Fl 8
48: .Op Fl E
49: .Op Fl F
50: .Op Fl K
51: .Op Fl L
52: .Op Fl S Ar tos
53: .Op Fl X Ar authtype
54: .Op Fl a
1.3 niklas 55: .Op Fl b Ar hostalias
1.1 deraadt 56: .Op Fl c
57: .Op Fl d
58: .Op Fl e Ar escapechar
59: .Op Fl f
60: .Op Fl k Ar realm
61: .Op Fl l Ar user
62: .Op Fl n Ar tracefile
63: .Op Fl r
64: .Op Fl x
65: .Oo
66: .Ar host
1.9 ! deraadt 67: .Op Ar port
1.1 deraadt 68: .Oc
69: .Sh DESCRIPTION
70: The
71: .Nm telnet
72: command
73: is used to communicate with another host using the
74: .Tn TELNET
75: protocol.
76: If
77: .Nm telnet
78: is invoked without the
79: .Ar host
80: argument, it enters command mode,
81: indicated by its prompt
82: .Pq Nm telnet\&> .
83: In this mode, it accepts and executes the commands listed below.
84: If it is invoked with arguments, it performs an
85: .Ic open
86: command with those arguments.
87: .Pp
88: Options:
89: .Bl -tag -width indent
90: .It Fl 8
91: Specifies an 8-bit data path. This causes an attempt to
92: negotiate the
93: .Dv TELNET BINARY
94: option on both input and output.
95: .It Fl E
96: Stops any character from being recognized as an escape character.
97: .It Fl F
98: If Kerberos V5 authentication is being used, the
99: .Fl F
100: option allows the local credentials to be forwarded
101: to the remote system, including any credentials that
102: have already been forwarded into the local environment.
103: .It Fl K
104: Specifies no automatic login to the remote system.
105: .It Fl L
106: Specifies an 8-bit data path on output. This causes the
107: BINARY option to be negotiated on output.
108: .It Fl S Ar tos
109: Sets the IP type-of-service (TOS) option for the telnet
110: connection to the value
111: .Ar tos,
112: which can be a numeric TOS value
113: or, on systems that support it, a symbolic
114: TOS name found in the /etc/iptos file.
115: .It Fl X Ar atype
116: Disables the
117: .Ar atype
118: type of authentication.
119: .It Fl a
120: Attempt automatic login.
121: Currently, this sends the user name via the
122: .Ev USER
123: variable
124: of the
125: .Ev ENVIRON
126: option if supported by the remote system.
127: The name used is that of the current user as returned by
128: .Xr getlogin 2
129: if it agrees with the current user ID,
130: otherwise it is the name associated with the user ID.
1.3 niklas 131: .It Fl b Ar hostalias
132: Uses
133: .Xr bind 2
134: on the local socket to bind it to an aliased address (See
135: .Xr ifconfig 8
136: and the \*(Lqalias\*(Rq specifier) or to the address of
137: another interface than the one naturally chosen by
138: .Xr connect 2 .
139: This can be useful when connecting to services which uses IP addresses
140: for authentication and reconfiguration of the server is undesirable (or
141: impossible).
1.1 deraadt 142: .It Fl c
143: Disables the reading of the user's
144: .Pa \&.telnetrc
145: file. (See the
146: .Ic toggle skiprc
147: command on this man page.)
148: .It Fl d
149: Sets the initial value of the
150: .Ic debug
151: toggle to
152: .Dv TRUE
1.8 deraadt 153: .It Fl e Ar escapechar
1.1 deraadt 154: Sets the initial
155: .Nm
156: escape character to
1.9 ! deraadt 157: .Ar escapechar Ns .
1.1 deraadt 158: If
1.8 deraadt 159: .Ar escapechar
1.1 deraadt 160: is omitted, then
161: there will be no escape character.
162: .It Fl f
163: If Kerberos V5 authentication is being used, the
164: .Fl f
165: option allows the local credentials to be forwarded to the remote system.
166: .It Fl k Ar realm
167: If Kerberos authentication is being used, the
168: .Fl k
169: option requests that telnet obtain tickets for the remote host in
1.8 deraadt 170: realm
171: .Ar realm
172: instead of the remote host's realm, as determined
1.1 deraadt 173: by
174: .Xr krb_realmofhost 3 .
175: .It Fl l Ar user
176: When connecting to the remote system, if the remote system
177: understands the
178: .Ev ENVIRON
179: option, then
180: .Ar user
181: will be sent to the remote system as the value for the variable USER.
182: This option implies the
183: .Fl a
184: option.
185: This option may also be used with the
186: .Ic open
187: command.
188: .It Fl n Ar tracefile
189: Opens
190: .Ar tracefile
191: for recording trace information.
192: See the
193: .Ic set tracefile
194: command below.
195: .It Fl r
196: Specifies a user interface similar to
197: .Xr rlogin 1 .
198: In this
199: mode, the escape character is set to the tilde (~) character,
1.8 deraadt 200: unless modified by the
201: .Fl e
202: option.
1.1 deraadt 203: .It Fl x
204: Turns on encryption of the data stream if possible. This
205: option is not available outside of the United States and
206: Canada.
207: .It Ar host
208: Indicates the official name, an alias, or the Internet address
209: of a remote host.
210: .It Ar port
211: Indicates a port number (address of an application). If a number is
212: not specified, the default
213: .Nm telnet
214: port is used.
215: .El
216: .Pp
217: When in rlogin mode, a line of the form ~. disconnects from the
218: remote host; ~ is the telnet escape character.
219: Similarly, the line ~^Z suspends the telnet session.
220: The line ~^] escapes to the normal telnet escape prompt.
221: .Pp
222: Once a connection has been opened,
223: .Nm telnet
224: will attempt to enable the
225: .Dv TELNET LINEMODE
226: option.
227: If this fails, then
228: .Nm telnet
229: will revert to one of two input modes:
230: either \*(Lqcharacter at a time\*(Rq
231: or \*(Lqold line by line\*(Rq
232: depending on what the remote system supports.
233: .Pp
234: When
235: .Dv LINEMODE
236: is enabled, character processing is done on the
237: local system, under the control of the remote system. When input
238: editing or character echoing is to be disabled, the remote system
239: will relay that information. 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
1.8 deraadt 282: .Dv BREAK .
1.1 deraadt 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 telnet
301: command mode may be entered by typing the
302: .Nm telnet
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 telnet
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. Valid arguments for the
326: auth command are as follows:
327: .Bl -tag -width "disable type"
328: .It Ic disable Ar type
329: Disables the specified type of authentication. To
330: obtain a list of available types, use the
331: .Ic auth disable \&?
332: command.
333: .It Ic enable Ar type
334: Enables the specified type of authentication. To
335: obtain a list of available types, use the
336: .Ic auth enable \&?
337: command.
338: .It Ic status
339: Lists the current status of the various types of
340: authentication.
341: .El
342: .It Ic close
343: Close a
344: .Tn TELNET
345: session and return to command mode.
346: .It Ic display Ar argument ...
347: Displays all, or some, of the
348: .Ic set
349: and
350: .Ic toggle
351: values (see below).
352: .It Ic encrypt Ar argument ...
353: The encrypt command manipulates the information sent through the
354: .Dv TELNET ENCRYPT
355: option.
356: .Pp
357: Note: Because of export controls, the
358: .Dv TELNET ENCRYPT
359: option is not supported outside of the United States and Canada.
360: .Pp
361: Valid arguments for the encrypt command are as follows:
362: .Bl -tag -width Ar
363: .It Ic disable Ar type Ic [input|output]
364: Disables the specified type of encryption. If you
365: omit the input and output, both input and output
366: are disabled. To obtain a list of available
367: types, use the
368: .Ic encrypt disable \&?
369: command.
370: .It Ic enable Ar type Ic [input|output]
371: Enables the specified type of encryption. If you
372: omit input and output, both input and output are
373: enabled. To obtain a list of available types, use the
374: .Ic encrypt enable \&?
375: command.
376: .It Ic input
377: This is the same as the
378: .Ic encrypt start input
379: command.
380: .It Ic -input
381: This is the same as the
382: .Ic encrypt stop input
383: command.
384: .It Ic output
385: This is the same as the
386: .Ic encrypt start output
387: command.
388: .It Ic -output
389: This is the same as the
390: .Ic encrypt stop output
391: command.
392: .It Ic start Ic [input|output]
393: Attempts to start encryption. If you omit
394: .Ic input
395: and
396: .Ic output,
397: both input and output are enabled. To
398: obtain a list of available types, use the
399: .Ic encrypt enable \&?
400: command.
401: .It Ic status
402: Lists the current status of encryption.
403: .It Ic stop Ic [input|output]
404: Stops encryption. If you omit input and output,
405: encryption is on both input and output.
406: .It Ic type Ar type
407: Sets the default type of encryption to be used
408: with later
409: .Ic encrypt start
410: or
411: .Ic encrypt stop
412: commands.
413: .El
414: .It Ic environ Ar arguments...
415: The
416: .Ic environ
417: command is used to manipulate the
1.8 deraadt 418: the variables that may be sent through the
1.1 deraadt 419: .Dv TELNET ENVIRON
420: option.
421: The initial set of variables is taken from the users
422: environment, with only the
423: .Ev DISPLAY
424: and
425: .Ev PRINTER
426: variables being exported by default.
427: The
428: .Ev USER
429: variable is also exported if the
430: .Fl a
431: or
432: .Fl l
433: options are used.
434: .br
435: Valid arguments for the
436: .Ic environ
437: command are:
438: .Bl -tag -width Fl
439: .It Ic define Ar variable value
440: Define the variable
441: .Ar variable
442: to have a value of
443: .Ar value.
444: Any variables defined by this command are automatically exported.
445: The
446: .Ar value
447: may be enclosed in single or double quotes so
448: that tabs and spaces may be included.
449: .It Ic undefine Ar variable
450: Remove
451: .Ar variable
452: from the list of environment variables.
453: .It Ic export Ar variable
454: Mark the variable
455: .Ar variable
456: to be exported to the remote side.
457: .It Ic unexport Ar variable
458: Mark the variable
459: .Ar variable
460: to not be exported unless
461: explicitly asked for by the remote side.
462: .It Ic list
463: List the current set of environment variables.
464: Those marked with a
465: .Cm *
466: will be sent automatically,
467: other variables will only be sent if explicitly requested.
468: .It Ic \&?
469: Prints out help information for the
470: .Ic environ
471: command.
472: .El
473: .It Ic logout
474: Sends the
475: .Dv TELNET LOGOUT
476: option to the remote side.
477: This command is similar to a
478: .Ic close
479: command; however, if the remote side does not support the
480: .Dv LOGOUT
481: option, nothing happens.
482: If, however, the remote side does support the
483: .Dv LOGOUT
484: option, this command should cause the remote side to close the
485: .Tn TELNET
486: connection.
487: If the remote side also supports the concept of
488: suspending a user's session for later reattachment,
489: the logout argument indicates that you
490: should terminate the session immediately.
491: .It Ic mode Ar type
492: .Ar Type
493: is one of several options, depending on the state of the
494: .Tn TELNET
495: session.
496: The remote host is asked for permission to go into the requested mode.
497: If the remote host is capable of entering that mode, the requested
498: mode will be entered.
499: .Bl -tag -width Ar
500: .It Ic character
501: Disable the
502: .Dv TELNET LINEMODE
503: option, or, if the remote side does not understand the
504: .Dv LINEMODE
505: option, then enter \*(Lqcharacter at a time\*(Lq mode.
506: .It Ic line
507: Enable the
508: .Dv TELNET LINEMODE
509: option, or, if the remote side does not understand the
510: .Dv LINEMODE
511: option, then attempt to enter \*(Lqold-line-by-line\*(Lq mode.
512: .It Ic isig Pq Ic \-isig
513: Attempt to enable (disable) the
514: .Dv TRAPSIG
515: mode of the
516: .Dv LINEMODE
517: option.
518: This requires that the
519: .Dv LINEMODE
520: option be enabled.
521: .It Ic edit Pq Ic \-edit
522: Attempt to enable (disable) the
523: .Dv EDIT
524: mode of the
525: .Dv LINEMODE
526: option.
527: This requires that the
528: .Dv LINEMODE
529: option be enabled.
530: .It Ic softtabs Pq Ic \-softtabs
531: Attempt to enable (disable) the
532: .Dv SOFT_TAB
533: mode of the
534: .Dv LINEMODE
535: option.
536: This requires that the
537: .Dv LINEMODE
538: option be enabled.
539: .It Ic litecho Pq Ic \-litecho
540: Attempt to enable (disable) the
541: .Dv LIT_ECHO
542: mode of the
543: .Dv LINEMODE
544: option.
545: This requires that the
546: .Dv LINEMODE
547: option be enabled.
548: .It Ic \&?
549: Prints out help information for the
550: .Ic mode
551: command.
552: .El
553: .It Xo
554: .Ic open Ar host
1.5 deraadt 555: .Op Fl l Ar user
556: .Oo Op Fl
1.1 deraadt 557: .Ar port Oc
558: .Xc
559: Open a connection to the named host.
560: If no port number
561: is specified,
562: .Nm telnet
563: will attempt to contact a
564: .Tn TELNET
565: server at the default port.
566: The host specification may be either a host name (see
1.7 deraadt 567: .Xr hosts 5 )
1.1 deraadt 568: or an Internet address specified in the \*(Lqdot notation\*(Rq (see
569: .Xr inet 3 ) .
570: The
1.5 deraadt 571: .Fl l
1.1 deraadt 572: option may be used to specify the user name
573: to be passed to the remote system via the
574: .Ev ENVIRON
575: option.
576: When connecting to a non-standard port,
577: .Nm telnet
578: omits any automatic initiation of
579: .Tn TELNET
580: options. When the port number is preceded by a minus sign,
581: the initial option negotiation is done.
582: After establishing a connection, the file
583: .Pa \&.telnetrc
584: in the
1.7 deraadt 585: user's home directory is opened. Lines beginning with a # are
1.1 deraadt 586: comment lines. Blank lines are ignored. Lines that begin
587: without white space are the start of a machine entry. The
588: first thing on the line is the name of the machine that is
589: being connected to. The rest of the line, and successive
590: lines that begin with white space are assumed to be
591: .Nm telnet
592: commands and are processed as if they had been typed
593: in manually to the
594: .Nm telnet
595: command prompt.
596: .It Ic quit
597: Close any open
598: .Tn TELNET
599: session and exit
600: .Nm telnet .
601: An end of file (in command mode) will also close a session and exit.
602: .It Ic send Ar arguments
603: Sends one or more special character sequences to the remote host.
604: The following are the arguments which may be specified
605: (more than one argument may be specified at a time):
606: .Pp
607: .Bl -tag -width escape
608: .It Ic abort
609: Sends the
610: .Dv TELNET ABORT
611: (Abort
612: processes)
613: sequence.
614: .It Ic ao
615: Sends the
616: .Dv TELNET AO
617: (Abort Output) sequence, which should cause the remote system to flush
618: all output
619: .Em from
620: the remote system
621: .Em to
622: the user's terminal.
623: .It Ic ayt
624: Sends the
625: .Dv TELNET AYT
626: (Are You There)
627: sequence, to which the remote system may or may not choose to respond.
628: .It Ic brk
629: Sends the
630: .Dv TELNET BRK
631: (Break) sequence, which may have significance to the remote
632: system.
633: .It Ic ec
634: Sends the
635: .Dv TELNET EC
636: (Erase Character)
637: sequence, which should cause the remote system to erase the last character
638: entered.
639: .It Ic el
640: Sends the
641: .Dv TELNET EL
642: (Erase Line)
643: sequence, which should cause the remote system to erase the line currently
644: being entered.
645: .It Ic eof
646: Sends the
647: .Dv TELNET EOF
648: (End Of File)
649: sequence.
650: .It Ic eor
651: Sends the
652: .Dv TELNET EOR
653: (End of Record)
654: sequence.
655: .It Ic escape
656: Sends the current
657: .Nm telnet
658: escape character (initially \*(Lq^\*(Rq).
659: .It Ic ga
660: Sends the
661: .Dv TELNET GA
662: (Go Ahead)
663: sequence, which likely has no significance to the remote system.
664: .It Ic getstatus
665: If the remote side supports the
666: .Dv TELNET STATUS
667: command,
668: .Ic getstatus
669: will send the subnegotiation to request that the server send
670: its current option status.
671: .It Ic ip
672: Sends the
673: .Dv TELNET IP
674: (Interrupt Process) sequence, which should cause the remote
675: system to abort the currently running process.
676: .It Ic nop
677: Sends the
678: .Dv TELNET NOP
679: (No OPeration)
680: sequence.
681: .It Ic susp
682: Sends the
683: .Dv TELNET SUSP
684: (SUSPend process)
685: sequence.
686: .It Ic synch
687: Sends the
688: .Dv TELNET SYNCH
689: sequence.
690: This sequence causes the remote system to discard all previously typed
691: (but not yet read) input.
692: This sequence is sent as
693: .Tn TCP
694: urgent
695: data (and may not work if the remote system is a
696: .Bx 4.2
697: system -- if
698: it doesn't work, a lower case \*(Lqr\*(Rq may be echoed on the terminal).
699: .It Ic do Ar cmd
700: .It Ic dont Ar cmd
701: .It Ic will Ar cmd
702: .It Ic wont Ar cmd
703: Sends the
704: .Dv TELNET DO
705: .Ar cmd
706: sequence.
707: .Ar Cmd
708: can be either a decimal number between 0 and 255,
709: or a symbolic name for a specific
710: .Dv TELNET
711: command.
712: .Ar Cmd
713: can also be either
714: .Ic help
715: or
716: .Ic \&?
717: to print out help information, including
718: a list of known symbolic names.
719: .It Ic \&?
720: Prints out help information for the
721: .Ic send
722: command.
723: .El
724: .It Ic set Ar argument value
725: .It Ic unset Ar argument value
726: The
727: .Ic set
728: command will set any one of a number of
729: .Nm telnet
730: variables to a specific value or to
731: .Dv TRUE .
732: The special value
733: .Ic off
734: turns off the function associated with
735: the variable, this is equivalent to using the
736: .Ic unset
737: command.
738: The
739: .Ic unset
740: command will disable or set to
741: .Dv FALSE
742: any of the specified functions.
743: The values of variables may be interrogated with the
744: .Ic display
745: command.
746: The variables which may be set or unset, but not toggled, are
747: listed here. In addition, any of the variables for the
748: .Ic toggle
749: command may be explicitly set or unset using
750: the
751: .Ic set
752: and
753: .Ic unset
754: commands.
755: .Bl -tag -width escape
756: .It Ic ayt
757: If
758: .Tn TELNET
759: is in localchars mode, or
760: .Dv LINEMODE
761: is enabled, and the status character is typed, a
762: .Dv TELNET AYT
763: sequence (see
764: .Ic send ayt
765: preceding) is sent to the
766: remote host. The initial value for the "Are You There"
767: character is the terminal's status character.
768: .It Ic echo
769: This is the value (initially \*(Lq^E\*(Rq) which, when in
770: \*(Lqline by line\*(Rq mode, toggles between doing local echoing
771: of entered characters (for normal processing), and suppressing
772: echoing of entered characters (for entering, say, a password).
773: .It Ic eof
774: If
775: .Nm telnet
776: is operating in
777: .Dv LINEMODE
778: or \*(Lqold line by line\*(Rq mode, entering this character
779: as the first character on a line will cause this character to be
780: sent to the remote system.
781: The initial value of the eof character is taken to be the terminal's
782: .Ic eof
783: character.
784: .It Ic erase
785: If
786: .Nm telnet
787: is in
788: .Ic localchars
789: mode (see
790: .Ic toggle
791: .Ic localchars
792: below),
793: .Sy and
794: if
795: .Nm telnet
796: is operating in \*(Lqcharacter at a time\*(Rq mode, then when this
797: character is typed, a
798: .Dv TELNET EC
799: sequence (see
800: .Ic send
801: .Ic ec
802: above)
803: is sent to the remote system.
804: The initial value for the erase character is taken to be
805: the terminal's
806: .Ic erase
807: character.
808: .It Ic escape
809: This is the
810: .Nm telnet
811: escape character (initially \*(Lq^[\*(Rq) which causes entry
812: into
813: .Nm telnet
814: command mode (when connected to a remote system).
815: .It Ic flushoutput
816: If
817: .Nm telnet
818: is in
819: .Ic localchars
820: mode (see
821: .Ic toggle
822: .Ic localchars
823: below)
824: and the
825: .Ic flushoutput
826: character is typed, a
827: .Dv TELNET AO
828: sequence (see
829: .Ic send
830: .Ic ao
831: above)
832: is sent to the remote host.
833: The initial value for the flush character is taken to be
834: the terminal's
835: .Ic flush
836: character.
837: .It Ic forw1
838: .It Ic forw2
839: If
840: .Tn TELNET
841: is operating in
842: .Dv LINEMODE ,
843: these are the
844: characters that, when typed, cause partial lines to be
845: forwarded to the remote system. The initial value for
846: the forwarding characters are taken from the terminal's
847: eol and eol2 characters.
848: .It Ic interrupt
849: If
850: .Nm telnet
851: is in
852: .Ic localchars
853: mode (see
854: .Ic toggle
855: .Ic localchars
856: below)
857: and the
858: .Ic interrupt
859: character is typed, a
860: .Dv TELNET IP
861: sequence (see
862: .Ic send
863: .Ic ip
864: above)
865: is sent to the remote host.
866: The initial value for the interrupt character is taken to be
867: the terminal's
868: .Ic intr
869: character.
870: .It Ic kill
871: If
872: .Nm telnet
873: is in
874: .Ic localchars
875: mode (see
876: .Ic toggle
877: .Ic localchars
878: below),
879: .Ic and
880: if
881: .Nm telnet
882: is operating in \*(Lqcharacter at a time\*(Rq mode, then when this
883: character is typed, a
884: .Dv TELNET EL
885: sequence (see
886: .Ic send
887: .Ic el
888: above)
889: is sent to the remote system.
890: The initial value for the kill character is taken to be
891: the terminal's
892: .Ic kill
893: character.
894: .It Ic lnext
895: If
896: .Nm telnet
897: is operating in
898: .Dv LINEMODE
899: or \*(Lqold line by line\*(Lq mode, then this character is taken to
900: be the terminal's
901: .Ic lnext
902: character.
903: The initial value for the lnext character is taken to be
904: the terminal's
905: .Ic lnext
906: character.
907: .It Ic quit
908: If
909: .Nm telnet
910: is in
911: .Ic localchars
912: mode (see
913: .Ic toggle
914: .Ic localchars
915: below)
916: and the
917: .Ic quit
918: character is typed, a
919: .Dv TELNET BRK
920: sequence (see
921: .Ic send
922: .Ic brk
923: above)
924: is sent to the remote host.
925: The initial value for the quit character is taken to be
926: the terminal's
927: .Ic quit
928: character.
929: .It Ic reprint
930: If
931: .Nm telnet
932: is operating in
933: .Dv LINEMODE
934: or \*(Lqold line by line\*(Lq mode, then this character is taken to
935: be the terminal's
936: .Ic reprint
937: character.
938: The initial value for the reprint character is taken to be
939: the terminal's
940: .Ic reprint
941: character.
942: .It Ic rlogin
943: This is the rlogin escape character.
944: If set, the normal
945: .Tn TELNET
946: escape character is ignored unless it is
947: preceded by this character at the beginning of a line.
948: This character, at the beginning of a line followed by
949: a "." closes the connection; when followed by a ^Z it
1.5 deraadt 950: suspends the
951: .Nm telnet
952: command. The initial state is to
1.1 deraadt 953: disable the rlogin escape character.
954: .It Ic start
955: If the
956: .Dv TELNET TOGGLE-FLOW-CONTROL
957: option has been enabled,
958: then this character is taken to
959: be the terminal's
960: .Ic start
961: character.
1.5 deraadt 962: The initial value for the start character is taken to be
1.1 deraadt 963: the terminal's
964: .Ic start
965: character.
966: .It Ic stop
967: If the
968: .Dv TELNET TOGGLE-FLOW-CONTROL
969: option has been enabled,
970: then this character is taken to
971: be the terminal's
972: .Ic stop
973: character.
1.5 deraadt 974: The initial value for the stop character is taken to be
1.1 deraadt 975: the terminal's
976: .Ic stop
977: character.
978: .It Ic susp
979: If
980: .Nm telnet
981: is in
982: .Ic localchars
983: mode, or
984: .Dv LINEMODE
985: is enabled, and the
986: .Ic suspend
987: character is typed, a
988: .Dv TELNET SUSP
989: sequence (see
990: .Ic send
991: .Ic susp
992: above)
993: is sent to the remote host.
994: The initial value for the suspend character is taken to be
995: the terminal's
996: .Ic suspend
997: character.
998: .It Ic tracefile
999: This is the file to which the output, caused by
1000: .Ic netdata
1001: or
1002: .Ic option
1003: tracing being
1004: .Dv TRUE ,
1005: will be written. If it is set to
1006: .Dq Fl ,
1007: then tracing information will be written to standard output (the default).
1008: .It Ic worderase
1009: If
1010: .Nm telnet
1011: is operating in
1012: .Dv LINEMODE
1013: or \*(Lqold line by line\*(Lq mode, then this character is taken to
1014: be the terminal's
1015: .Ic worderase
1016: character.
1017: The initial value for the worderase character is taken to be
1018: the terminal's
1019: .Ic worderase
1020: character.
1021: .It Ic \&?
1022: Displays the legal
1023: .Ic set
1024: .Pq Ic unset
1025: commands.
1026: .El
1027: .It Ic slc Ar state
1028: The
1029: .Ic slc
1030: command (Set Local Characters) is used to set
1.4 deraadt 1031: or change the state of the special
1.1 deraadt 1032: characters when the
1033: .Dv TELNET LINEMODE
1034: option has
1035: been enabled. Special characters are characters that get
1036: mapped to
1037: .Tn TELNET
1038: commands sequences (like
1039: .Ic ip
1040: or
1041: .Ic quit )
1042: or line editing characters (like
1043: .Ic erase
1044: and
1045: .Ic kill ) .
1046: By default, the local special characters are exported.
1047: .Bl -tag -width Fl
1048: .It Ic check
1049: Verify the current settings for the current special characters.
1050: The remote side is requested to send all the current special
1051: character settings, and if there are any discrepancies with
1052: the local side, the local side will switch to the remote value.
1053: .It Ic export
1054: Switch to the local defaults for the special characters. The
1055: local default characters are those of the local terminal at
1056: the time when
1057: .Nm telnet
1058: was started.
1059: .It Ic import
1060: Switch to the remote defaults for the special characters.
1061: The remote default characters are those of the remote system
1062: at the time when the
1063: .Tn TELNET
1064: connection was established.
1065: .It Ic \&?
1066: Prints out help information for the
1067: .Ic slc
1068: command.
1069: .El
1070: .It Ic status
1071: Show the current status of
1072: .Nm telnet .
1073: This includes the peer one is connected to, as well
1074: as the current mode.
1075: .It Ic toggle Ar arguments ...
1076: Toggle (between
1077: .Dv TRUE
1078: and
1079: .Dv FALSE )
1080: various flags that control how
1081: .Nm telnet
1082: responds to events.
1083: These flags may be set explicitly to
1084: .Dv TRUE
1085: or
1086: .Dv FALSE
1087: using the
1088: .Ic set
1089: and
1090: .Ic unset
1091: commands listed above.
1092: More than one argument may be specified.
1093: The state of these flags may be interrogated with the
1094: .Ic display
1095: command.
1096: Valid arguments are:
1097: .Bl -tag -width Ar
1098: .It Ic authdebug
1099: Turns on debugging information for the authentication code.
1100: .It Ic autoflush
1101: If
1102: .Ic autoflush
1103: and
1104: .Ic localchars
1105: are both
1106: .Dv TRUE ,
1107: then when the
1108: .Ic ao ,
1109: or
1110: .Ic quit
1111: characters are recognized (and transformed into
1112: .Tn TELNET
1113: sequences; see
1114: .Ic set
1115: above for details),
1116: .Nm telnet
1117: refuses to display any data on the user's terminal
1118: until the remote system acknowledges (via a
1119: .Dv TELNET TIMING MARK
1120: option)
1121: that it has processed those
1122: .Tn TELNET
1123: sequences.
1124: The initial value for this toggle is
1125: .Dv TRUE
1126: if the terminal user had not
1127: done an "stty noflsh", otherwise
1128: .Dv FALSE
1129: (see
1130: .Xr stty 1 ) .
1131: .It Ic autodecrypt
1132: When the
1133: .Dv TELNET ENCRYPT
1134: option is negotiated, by
1135: default the actual encryption (decryption) of the data
1136: stream does not start automatically. The autoencrypt
1137: (autodecrypt) command states that encryption of the
1138: output (input) stream should be enabled as soon as
1139: possible.
1140: .Pp
1141: Note: Because of export controls, the
1142: .Dv TELNET ENCRYPT
1143: option is not supported outside the United States and Canada.
1144: .It Ic autologin
1145: If the remote side supports the
1146: .Dv TELNET AUTHENTICATION
1147: option
1148: .Tn TELNET
1149: attempts to use it to perform automatic authentication. If the
1150: .Dv AUTHENTICATION
1151: option is not supported, the user's login
1152: name are propagated through the
1153: .Dv TELNET ENVIRON
1154: option.
1155: This command is the same as specifying
1156: .Ar a
1157: option on the
1158: .Ic open
1159: command.
1160: .It Ic autosynch
1161: If
1162: .Ic autosynch
1163: and
1164: .Ic localchars
1165: are both
1166: .Dv TRUE ,
1167: then when either the
1168: .Ic intr
1169: or
1170: .Ic quit
1171: characters is typed (see
1172: .Ic set
1173: above for descriptions of the
1174: .Ic intr
1175: and
1176: .Ic quit
1177: characters), the resulting
1178: .Tn TELNET
1179: sequence sent is followed by the
1180: .Dv TELNET SYNCH
1181: sequence.
1182: This procedure
1183: .Ic should
1184: cause the remote system to begin throwing away all previously
1185: typed input until both of the
1186: .Tn TELNET
1187: sequences have been read and acted upon.
1188: The initial value of this toggle is
1189: .Dv FALSE .
1190: .It Ic binary
1191: Enable or disable the
1192: .Dv TELNET BINARY
1193: option on both input and output.
1194: .It Ic inbinary
1195: Enable or disable the
1196: .Dv TELNET BINARY
1197: option on input.
1198: .It Ic outbinary
1199: Enable or disable the
1200: .Dv TELNET BINARY
1201: option on output.
1202: .It Ic crlf
1203: If this is
1204: .Dv TRUE ,
1205: then carriage returns will be sent as
1206: .Li <CR><LF> .
1207: If this is
1208: .Dv FALSE ,
1209: then carriage returns will be send as
1210: .Li <CR><NUL> .
1211: The initial value for this toggle is
1212: .Dv FALSE .
1213: .It Ic crmod
1214: Toggle carriage return mode.
1215: When this mode is enabled, most carriage return characters received from
1216: the remote host will be mapped into a carriage return followed by
1217: a line feed.
1218: This mode does not affect those characters typed by the user, only
1219: those received from the remote host.
1220: This mode is not very useful unless the remote host
1221: only sends carriage return, but never line feed.
1222: The initial value for this toggle is
1223: .Dv FALSE .
1224: .It Ic debug
1225: Toggles socket level debugging (useful only to the
1226: .Ic super user ) .
1227: The initial value for this toggle is
1228: .Dv FALSE .
1229: .It Ic encdebug
1230: Turns on debugging information for the encryption code.
1231: .It Ic localchars
1232: If this is
1233: .Dv TRUE ,
1234: then the
1235: .Ic flush ,
1236: .Ic interrupt ,
1237: .Ic quit ,
1238: .Ic erase ,
1239: and
1240: .Ic kill
1241: characters (see
1242: .Ic set
1243: above) are recognized locally, and transformed into (hopefully) appropriate
1244: .Tn TELNET
1245: control sequences
1246: (respectively
1247: .Ic ao ,
1248: .Ic ip ,
1249: .Ic brk ,
1250: .Ic ec ,
1251: and
1252: .Ic el ;
1253: see
1254: .Ic send
1255: above).
1256: The initial value for this toggle is
1257: .Dv TRUE
1258: in \*(Lqold line by line\*(Rq mode,
1259: and
1260: .Dv FALSE
1261: in \*(Lqcharacter at a time\*(Rq mode.
1262: When the
1263: .Dv LINEMODE
1264: option is enabled, the value of
1265: .Ic localchars
1266: is ignored, and assumed to always be
1267: .Dv TRUE .
1268: If
1269: .Dv LINEMODE
1270: has ever been enabled, then
1271: .Ic quit
1272: is sent as
1273: .Ic abort ,
1274: and
1275: .Ic eof and
1.5 deraadt 1276: .Ic suspend
1.1 deraadt 1277: are sent as
1278: .Ic eof and
1.5 deraadt 1279: .Ic susp
1280: (see
1.1 deraadt 1281: .Ic send
1282: above).
1283: .It Ic netdata
1284: Toggles the display of all network data (in hexadecimal format).
1285: The initial value for this toggle is
1286: .Dv FALSE .
1287: .It Ic options
1288: Toggles the display of some internal
1289: .Nm telnet
1290: protocol processing (having to do with
1291: .Tn TELNET
1292: options).
1293: The initial value for this toggle is
1294: .Dv FALSE .
1295: .It Ic prettydump
1296: When the
1297: .Ic netdata
1298: toggle is enabled, if
1299: .Ic prettydump
1300: is enabled the output from the
1301: .Ic netdata
1302: command will be formatted in a more user readable format.
1303: Spaces are put between each character in the output, and the
1304: beginning of any
1305: .Tn TELNET
1306: escape sequence is preceded by a '*' to aid in locating them.
1307: .It Ic skiprc
1308: When the skiprc toggle is
1309: .Dv TRUE ,
1310: .Tn TELNET
1311: skips the reading of the
1312: .Pa \&.telnetrc
1313: file in the users home
1314: directory when connections are opened. The initial
1315: value for this toggle is
1316: .Dv FALSE.
1317: .It Ic termdata
1318: Toggles the display of all terminal data (in hexadecimal format).
1319: The initial value for this toggle is
1320: .Dv FALSE .
1321: .It Ic verbose_encrypt
1322: When the
1323: .Ic verbose_encrypt
1324: toggle is
1325: .Dv TRUE ,
1.5 deraadt 1326: .Nm telnet
1.1 deraadt 1327: prints out a message each time encryption is enabled or
1328: disabled. The initial value for this toggle is
1329: .Dv FALSE.
1330: Note: Because of export controls, data encryption
1331: is not supported outside of the United States and Canada.
1332: .It Ic \&?
1333: Displays the legal
1334: .Ic toggle
1335: commands.
1336: .El
1337: .It Ic z
1338: Suspend
1339: .Nm telnet .
1340: This command only works when the user is using the
1341: .Xr csh 1 .
1342: .It Ic \&! Op Ar command
1343: Execute a single command in a subshell on the local
1344: system. If
1.5 deraadt 1345: .Ar command
1.1 deraadt 1346: is omitted, then an interactive
1347: subshell is invoked.
1348: .It Ic \&? Op Ar command
1349: Get help. With no arguments,
1350: .Nm telnet
1351: prints a help summary.
1352: If a command is specified,
1353: .Nm telnet
1354: will print the help information for just that command.
1355: .El
1356: .Sh ENVIRONMENT
1357: .Nm Telnet
1358: uses at least the
1359: .Ev HOME ,
1360: .Ev SHELL ,
1361: .Ev DISPLAY ,
1362: and
1363: .Ev TERM
1364: environment variables.
1365: Other environment variables may be propagated
1366: to the other side via the
1367: .Dv TELNET ENVIRON
1368: option.
1369: .Sh FILES
1370: .Bl -tag -width ~/.telnetrc -compact
1371: .It Pa ~/.telnetrc
1372: user customized telnet startup values
1373: .El
1374: .Sh HISTORY
1375: The
1376: .Nm Telnet
1377: command appeared in
1378: .Bx 4.2 .
1379: .Sh NOTES
1380: .Pp
1381: On some remote systems, echo has to be turned off manually when in
1382: \*(Lqold line by line\*(Rq mode.
1383: .Pp
1384: In \*(Lqold line by line\*(Rq mode or
1385: .Dv LINEMODE
1386: the terminal's
1387: .Ic eof
1388: character is only recognized (and sent to the remote system)
1389: when it is the first character on a line.
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