Annotation of src/usr.bin/telnet/telnet.1, Revision 1.7
1.7 ! deraadt 1: .\" $OpenBSD: telnet.1,v 1.6 1997/05/31 05:59:05 deraadt Exp $
1.2 niklas 2: .\" $NetBSD: telnet.1,v 1.5 1996/02/28 21:04:12 thorpej Exp $
3: .\"
1.1 deraadt 4: .\" Copyright (c) 1983, 1990, 1993
5: .\" The Regents of the University of California. All rights reserved.
6: .\"
7: .\" Redistribution and use in source and binary forms, with or without
8: .\" modification, are permitted provided that the following conditions
9: .\" are met:
10: .\" 1. Redistributions of source code must retain the above copyright
11: .\" notice, this list of conditions and the following disclaimer.
12: .\" 2. Redistributions in binary form must reproduce the above copyright
13: .\" notice, this list of conditions and the following disclaimer in the
14: .\" documentation and/or other materials provided with the distribution.
15: .\" 3. All advertising materials mentioning features or use of this software
16: .\" must display the following acknowledgement:
17: .\" This product includes software developed by the University of
18: .\" California, Berkeley and its contributors.
19: .\" 4. Neither the name of the University nor the names of its contributors
20: .\" may be used to endorse or promote products derived from this software
21: .\" without specific prior written permission.
22: .\"
23: .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24: .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25: .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26: .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27: .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28: .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29: .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30: .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31: .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32: .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33: .\" SUCH DAMAGE.
34: .\"
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
67: .Op port
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
153: .It Fl e Ar escape char
154: Sets the initial
155: .Nm
156: escape character to
157: .Ar escape char.
158: If
159: .Ar escape char
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
170: realm realm instead of the remote host's realm, as determined
171: by
172: .Xr krb_realmofhost 3 .
173: .It Fl l Ar user
174: When connecting to the remote system, if the remote system
175: understands the
176: .Ev ENVIRON
177: option, then
178: .Ar user
179: will be sent to the remote system as the value for the variable USER.
180: This option implies the
181: .Fl a
182: option.
183: This option may also be used with the
184: .Ic open
185: command.
186: .It Fl n Ar tracefile
187: Opens
188: .Ar tracefile
189: for recording trace information.
190: See the
191: .Ic set tracefile
192: command below.
193: .It Fl r
194: Specifies a user interface similar to
195: .Xr rlogin 1 .
196: In this
197: mode, the escape character is set to the tilde (~) character,
198: unless modified by the -e option.
199: .It Fl x
200: Turns on encryption of the data stream if possible. 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). If a number is
208: not specified, the default
209: .Nm telnet
210: port is used.
211: .El
212: .Pp
213: When in rlogin mode, a line of the form ~. disconnects from the
214: remote host; ~ is the telnet escape character.
215: Similarly, the line ~^Z suspends the telnet session.
216: The line ~^] escapes to the normal telnet escape prompt.
217: .Pp
218: Once a connection has been opened,
219: .Nm telnet
220: will attempt to enable the
221: .Dv TELNET LINEMODE
222: option.
223: If this fails, then
224: .Nm telnet
225: will revert to one of two input modes:
226: either \*(Lqcharacter at a time\*(Rq
227: or \*(Lqold line by line\*(Rq
228: depending on what the remote system supports.
229: .Pp
230: When
231: .Dv LINEMODE
232: is enabled, character processing is done on the
233: local system, under the control of the remote system. When input
234: editing or character echoing is to be disabled, the remote system
235: will relay that information. The remote system will also relay
236: changes to any special characters that happen on the remote
237: system, so that they can take effect on the local system.
238: .Pp
239: In \*(Lqcharacter at a time\*(Rq mode, most
240: text typed is immediately sent to the remote host for processing.
241: .Pp
242: In \*(Lqold line by line\*(Rq mode, all text is echoed locally,
243: and (normally) only completed lines are sent to the remote host.
244: The \*(Lqlocal echo character\*(Rq (initially \*(Lq^E\*(Rq) may be used
245: to turn off and on the local echo
246: (this would mostly be used to enter passwords
247: without the password being echoed).
248: .Pp
249: If the
250: .Dv LINEMODE
251: option is enabled, or if the
252: .Ic localchars
253: toggle is
254: .Dv TRUE
255: (the default for \*(Lqold line by line\*(Lq; see below),
256: the user's
257: .Ic quit ,
258: .Ic intr ,
259: and
260: .Ic flush
261: characters are trapped locally, and sent as
262: .Tn TELNET
263: protocol sequences to the remote side.
264: If
265: .Dv LINEMODE
266: has ever been enabled, then the user's
267: .Ic susp
268: and
269: .Ic eof
270: are also sent as
271: .Tn TELNET
272: protocol sequences,
273: and
274: .Ic quit
275: is sent as a
276: .Dv TELNET ABORT
277: instead of
278: .Dv BREAK
279: There are options (see
280: .Ic toggle
281: .Ic autoflush
282: and
283: .Ic toggle
284: .Ic autosynch
285: below)
286: which cause this action to flush subsequent output to the terminal
287: (until the remote host acknowledges the
288: .Tn TELNET
289: sequence) and flush previous terminal input
290: (in the case of
291: .Ic quit
292: and
293: .Ic intr ) .
294: .Pp
295: While connected to a remote host,
296: .Nm telnet
297: command mode may be entered by typing the
298: .Nm telnet
299: \*(Lqescape character\*(Rq (initially \*(Lq^]\*(Rq).
300: When in command mode, the normal terminal editing conventions are available.
301: .Pp
302: The following
303: .Nm telnet
304: commands are available.
305: Only enough of each command to uniquely identify it need be typed
306: (this is also true for arguments to the
307: .Ic mode ,
308: .Ic set ,
309: .Ic toggle ,
310: .Ic unset ,
311: .Ic slc ,
312: .Ic environ ,
313: and
314: .Ic display
315: commands).
316: .Pp
317: .Bl -tag -width "mode type"
318: .It Ic auth Ar argument ...
319: The auth command manipulates the information sent through the
320: .Dv TELNET AUTHENTICATE
321: option. Valid arguments for the
322: auth command are as follows:
323: .Bl -tag -width "disable type"
324: .It Ic disable Ar type
325: Disables the specified type of authentication. To
326: obtain a list of available types, use the
327: .Ic auth disable \&?
328: command.
329: .It Ic enable Ar type
330: Enables the specified type of authentication. To
331: obtain a list of available types, use the
332: .Ic auth enable \&?
333: command.
334: .It Ic status
335: Lists the current status of the various types of
336: authentication.
337: .El
338: .It Ic close
339: Close a
340: .Tn TELNET
341: session and return to command mode.
342: .It Ic display Ar argument ...
343: Displays all, or some, of the
344: .Ic set
345: and
346: .Ic toggle
347: values (see below).
348: .It Ic encrypt Ar argument ...
349: The encrypt command manipulates the information sent through the
350: .Dv TELNET ENCRYPT
351: option.
352: .Pp
353: Note: Because of export controls, the
354: .Dv TELNET ENCRYPT
355: option is not supported outside of the United States and Canada.
356: .Pp
357: Valid arguments for the encrypt command are as follows:
358: .Bl -tag -width Ar
359: .It Ic disable Ar type Ic [input|output]
360: Disables the specified type of encryption. If you
361: omit the input and output, both input and output
362: are disabled. To obtain a list of available
363: types, use the
364: .Ic encrypt disable \&?
365: command.
366: .It Ic enable Ar type Ic [input|output]
367: Enables the specified type of encryption. If you
368: omit input and output, both input and output are
369: enabled. To obtain a list of available types, use the
370: .Ic encrypt enable \&?
371: command.
372: .It Ic input
373: This is the same as the
374: .Ic encrypt start input
375: command.
376: .It Ic -input
377: This is the same as the
378: .Ic encrypt stop input
379: command.
380: .It Ic output
381: This is the same as the
382: .Ic encrypt start output
383: command.
384: .It Ic -output
385: This is the same as the
386: .Ic encrypt stop output
387: command.
388: .It Ic start Ic [input|output]
389: Attempts to start encryption. If you omit
390: .Ic input
391: and
392: .Ic output,
393: both input and output are enabled. To
394: obtain a list of available types, use the
395: .Ic encrypt enable \&?
396: command.
397: .It Ic status
398: Lists the current status of encryption.
399: .It Ic stop Ic [input|output]
400: Stops encryption. If you omit input and output,
401: encryption is on both input and output.
402: .It Ic type Ar type
403: Sets the default type of encryption to be used
404: with later
405: .Ic encrypt start
406: or
407: .Ic encrypt stop
408: commands.
409: .El
410: .It Ic environ Ar arguments...
411: The
412: .Ic environ
413: command is used to manipulate the
414: the variables that my be sent through the
415: .Dv TELNET ENVIRON
416: option.
417: The initial set of variables is taken from the users
418: environment, with only the
419: .Ev DISPLAY
420: and
421: .Ev PRINTER
422: variables being exported by default.
423: The
424: .Ev USER
425: variable is also exported if the
426: .Fl a
427: or
428: .Fl l
429: options are used.
430: .br
431: Valid arguments for the
432: .Ic environ
433: command are:
434: .Bl -tag -width Fl
435: .It Ic define Ar variable value
436: Define the variable
437: .Ar variable
438: to have a value of
439: .Ar value.
440: Any variables defined by this command are automatically exported.
441: The
442: .Ar value
443: may be enclosed in single or double quotes so
444: that tabs and spaces may be included.
445: .It Ic undefine Ar variable
446: Remove
447: .Ar variable
448: from the list of environment variables.
449: .It Ic export Ar variable
450: Mark the variable
451: .Ar variable
452: to be exported to the remote side.
453: .It Ic unexport Ar variable
454: Mark the variable
455: .Ar variable
456: to not be exported unless
457: explicitly asked for by the remote side.
458: .It Ic list
459: List the current set of environment variables.
460: Those marked with a
461: .Cm *
462: will be sent automatically,
463: other variables will only be sent if explicitly requested.
464: .It Ic \&?
465: Prints out help information for the
466: .Ic environ
467: command.
468: .El
469: .It Ic logout
470: Sends the
471: .Dv TELNET LOGOUT
472: option to the remote side.
473: This command is similar to a
474: .Ic close
475: command; however, if the remote side does not support the
476: .Dv LOGOUT
477: option, nothing happens.
478: If, however, the remote side does support the
479: .Dv LOGOUT
480: option, this command should cause the remote side to close the
481: .Tn TELNET
482: connection.
483: If the remote side also supports the concept of
484: suspending a user's session for later reattachment,
485: the logout argument indicates that you
486: should terminate the session immediately.
487: .It Ic mode Ar type
488: .Ar Type
489: is one of several options, depending on the state of the
490: .Tn TELNET
491: session.
492: The remote host is asked for permission to go into the requested mode.
493: If the remote host is capable of entering that mode, the requested
494: mode will be entered.
495: .Bl -tag -width Ar
496: .It Ic character
497: Disable the
498: .Dv TELNET LINEMODE
499: option, or, if the remote side does not understand the
500: .Dv LINEMODE
501: option, then enter \*(Lqcharacter at a time\*(Lq mode.
502: .It Ic line
503: Enable the
504: .Dv TELNET LINEMODE
505: option, or, if the remote side does not understand the
506: .Dv LINEMODE
507: option, then attempt to enter \*(Lqold-line-by-line\*(Lq mode.
508: .It Ic isig Pq Ic \-isig
509: Attempt to enable (disable) the
510: .Dv TRAPSIG
511: mode of the
512: .Dv LINEMODE
513: option.
514: This requires that the
515: .Dv LINEMODE
516: option be enabled.
517: .It Ic edit Pq Ic \-edit
518: Attempt to enable (disable) the
519: .Dv EDIT
520: mode of the
521: .Dv LINEMODE
522: option.
523: This requires that the
524: .Dv LINEMODE
525: option be enabled.
526: .It Ic softtabs Pq Ic \-softtabs
527: Attempt to enable (disable) the
528: .Dv SOFT_TAB
529: mode of the
530: .Dv LINEMODE
531: option.
532: This requires that the
533: .Dv LINEMODE
534: option be enabled.
535: .It Ic litecho Pq Ic \-litecho
536: Attempt to enable (disable) the
537: .Dv LIT_ECHO
538: mode of the
539: .Dv LINEMODE
540: option.
541: This requires that the
542: .Dv LINEMODE
543: option be enabled.
544: .It Ic \&?
545: Prints out help information for the
546: .Ic mode
547: command.
548: .El
549: .It Xo
550: .Ic open Ar host
1.5 deraadt 551: .Op Fl l Ar user
552: .Oo Op Fl
1.1 deraadt 553: .Ar port Oc
554: .Xc
555: Open a connection to the named host.
556: If no port number
557: is specified,
558: .Nm telnet
559: will attempt to contact a
560: .Tn TELNET
561: server at the default port.
562: The host specification may be either a host name (see
1.7 ! deraadt 563: .Xr hosts 5 )
1.1 deraadt 564: or an Internet address specified in the \*(Lqdot notation\*(Rq (see
565: .Xr inet 3 ) .
566: The
1.5 deraadt 567: .Fl l
1.1 deraadt 568: option may be used to specify the user name
569: to be passed to the remote system via the
570: .Ev ENVIRON
571: option.
572: When connecting to a non-standard port,
573: .Nm telnet
574: omits any automatic initiation of
575: .Tn TELNET
576: options. When the port number is preceded by a minus sign,
577: the initial option negotiation is done.
578: After establishing a connection, the file
579: .Pa \&.telnetrc
580: in the
1.7 ! deraadt 581: user's home directory is opened. Lines beginning with a # are
1.1 deraadt 582: comment lines. Blank lines are ignored. Lines that begin
583: without white space are the start of a machine entry. The
584: first thing on the line is the name of the machine that is
585: being connected to. The rest of the line, and successive
586: lines that begin with white space are assumed to be
587: .Nm telnet
588: commands and are processed as if they had been typed
589: in manually to the
590: .Nm telnet
591: command prompt.
592: .It Ic quit
593: Close any open
594: .Tn TELNET
595: session and exit
596: .Nm telnet .
597: An end of file (in command mode) will also close a session and exit.
598: .It Ic send Ar arguments
599: Sends one or more special character sequences to the remote host.
600: The following are the arguments which may be specified
601: (more than one argument may be specified at a time):
602: .Pp
603: .Bl -tag -width escape
604: .It Ic abort
605: Sends the
606: .Dv TELNET ABORT
607: (Abort
608: processes)
609: sequence.
610: .It Ic ao
611: Sends the
612: .Dv TELNET AO
613: (Abort Output) sequence, which should cause the remote system to flush
614: all output
615: .Em from
616: the remote system
617: .Em to
618: the user's terminal.
619: .It Ic ayt
620: Sends the
621: .Dv TELNET AYT
622: (Are You There)
623: sequence, to which the remote system may or may not choose to respond.
624: .It Ic brk
625: Sends the
626: .Dv TELNET BRK
627: (Break) sequence, which may have significance to the remote
628: system.
629: .It Ic ec
630: Sends the
631: .Dv TELNET EC
632: (Erase Character)
633: sequence, which should cause the remote system to erase the last character
634: entered.
635: .It Ic el
636: Sends the
637: .Dv TELNET EL
638: (Erase Line)
639: sequence, which should cause the remote system to erase the line currently
640: being entered.
641: .It Ic eof
642: Sends the
643: .Dv TELNET EOF
644: (End Of File)
645: sequence.
646: .It Ic eor
647: Sends the
648: .Dv TELNET EOR
649: (End of Record)
650: sequence.
651: .It Ic escape
652: Sends the current
653: .Nm telnet
654: escape character (initially \*(Lq^\*(Rq).
655: .It Ic ga
656: Sends the
657: .Dv TELNET GA
658: (Go Ahead)
659: sequence, which likely has no significance to the remote system.
660: .It Ic getstatus
661: If the remote side supports the
662: .Dv TELNET STATUS
663: command,
664: .Ic getstatus
665: will send the subnegotiation to request that the server send
666: its current option status.
667: .It Ic ip
668: Sends the
669: .Dv TELNET IP
670: (Interrupt Process) sequence, which should cause the remote
671: system to abort the currently running process.
672: .It Ic nop
673: Sends the
674: .Dv TELNET NOP
675: (No OPeration)
676: sequence.
677: .It Ic susp
678: Sends the
679: .Dv TELNET SUSP
680: (SUSPend process)
681: sequence.
682: .It Ic synch
683: Sends the
684: .Dv TELNET SYNCH
685: sequence.
686: This sequence causes the remote system to discard all previously typed
687: (but not yet read) input.
688: This sequence is sent as
689: .Tn TCP
690: urgent
691: data (and may not work if the remote system is a
692: .Bx 4.2
693: system -- if
694: it doesn't work, a lower case \*(Lqr\*(Rq may be echoed on the terminal).
695: .It Ic do Ar cmd
696: .It Ic dont Ar cmd
697: .It Ic will Ar cmd
698: .It Ic wont Ar cmd
699: Sends the
700: .Dv TELNET DO
701: .Ar cmd
702: sequence.
703: .Ar Cmd
704: can be either a decimal number between 0 and 255,
705: or a symbolic name for a specific
706: .Dv TELNET
707: command.
708: .Ar Cmd
709: can also be either
710: .Ic help
711: or
712: .Ic \&?
713: to print out help information, including
714: a list of known symbolic names.
715: .It Ic \&?
716: Prints out help information for the
717: .Ic send
718: command.
719: .El
720: .It Ic set Ar argument value
721: .It Ic unset Ar argument value
722: The
723: .Ic set
724: command will set any one of a number of
725: .Nm telnet
726: variables to a specific value or to
727: .Dv TRUE .
728: The special value
729: .Ic off
730: turns off the function associated with
731: the variable, this is equivalent to using the
732: .Ic unset
733: command.
734: The
735: .Ic unset
736: command will disable or set to
737: .Dv FALSE
738: any of the specified functions.
739: The values of variables may be interrogated with the
740: .Ic display
741: command.
742: The variables which may be set or unset, but not toggled, are
743: listed here. In addition, any of the variables for the
744: .Ic toggle
745: command may be explicitly set or unset using
746: the
747: .Ic set
748: and
749: .Ic unset
750: commands.
751: .Bl -tag -width escape
752: .It Ic ayt
753: If
754: .Tn TELNET
755: is in localchars mode, or
756: .Dv LINEMODE
757: is enabled, and the status character is typed, a
758: .Dv TELNET AYT
759: sequence (see
760: .Ic send ayt
761: preceding) is sent to the
762: remote host. The initial value for the "Are You There"
763: character is the terminal's status character.
764: .It Ic echo
765: This is the value (initially \*(Lq^E\*(Rq) which, when in
766: \*(Lqline by line\*(Rq mode, toggles between doing local echoing
767: of entered characters (for normal processing), and suppressing
768: echoing of entered characters (for entering, say, a password).
769: .It Ic eof
770: If
771: .Nm telnet
772: is operating in
773: .Dv LINEMODE
774: or \*(Lqold line by line\*(Rq mode, entering this character
775: as the first character on a line will cause this character to be
776: sent to the remote system.
777: The initial value of the eof character is taken to be the terminal's
778: .Ic eof
779: character.
780: .It Ic erase
781: If
782: .Nm telnet
783: is in
784: .Ic localchars
785: mode (see
786: .Ic toggle
787: .Ic localchars
788: below),
789: .Sy and
790: if
791: .Nm telnet
792: is operating in \*(Lqcharacter at a time\*(Rq mode, then when this
793: character is typed, a
794: .Dv TELNET EC
795: sequence (see
796: .Ic send
797: .Ic ec
798: above)
799: is sent to the remote system.
800: The initial value for the erase character is taken to be
801: the terminal's
802: .Ic erase
803: character.
804: .It Ic escape
805: This is the
806: .Nm telnet
807: escape character (initially \*(Lq^[\*(Rq) which causes entry
808: into
809: .Nm telnet
810: command mode (when connected to a remote system).
811: .It Ic flushoutput
812: If
813: .Nm telnet
814: is in
815: .Ic localchars
816: mode (see
817: .Ic toggle
818: .Ic localchars
819: below)
820: and the
821: .Ic flushoutput
822: character is typed, a
823: .Dv TELNET AO
824: sequence (see
825: .Ic send
826: .Ic ao
827: above)
828: is sent to the remote host.
829: The initial value for the flush character is taken to be
830: the terminal's
831: .Ic flush
832: character.
833: .It Ic forw1
834: .It Ic forw2
835: If
836: .Tn TELNET
837: is operating in
838: .Dv LINEMODE ,
839: these are the
840: characters that, when typed, cause partial lines to be
841: forwarded to the remote system. The initial value for
842: the forwarding characters are taken from the terminal's
843: eol and eol2 characters.
844: .It Ic interrupt
845: If
846: .Nm telnet
847: is in
848: .Ic localchars
849: mode (see
850: .Ic toggle
851: .Ic localchars
852: below)
853: and the
854: .Ic interrupt
855: character is typed, a
856: .Dv TELNET IP
857: sequence (see
858: .Ic send
859: .Ic ip
860: above)
861: is sent to the remote host.
862: The initial value for the interrupt character is taken to be
863: the terminal's
864: .Ic intr
865: character.
866: .It Ic kill
867: If
868: .Nm telnet
869: is in
870: .Ic localchars
871: mode (see
872: .Ic toggle
873: .Ic localchars
874: below),
875: .Ic and
876: if
877: .Nm telnet
878: is operating in \*(Lqcharacter at a time\*(Rq mode, then when this
879: character is typed, a
880: .Dv TELNET EL
881: sequence (see
882: .Ic send
883: .Ic el
884: above)
885: is sent to the remote system.
886: The initial value for the kill character is taken to be
887: the terminal's
888: .Ic kill
889: character.
890: .It Ic lnext
891: If
892: .Nm telnet
893: is operating in
894: .Dv LINEMODE
895: or \*(Lqold line by line\*(Lq mode, then this character is taken to
896: be the terminal's
897: .Ic lnext
898: character.
899: The initial value for the lnext character is taken to be
900: the terminal's
901: .Ic lnext
902: character.
903: .It Ic quit
904: If
905: .Nm telnet
906: is in
907: .Ic localchars
908: mode (see
909: .Ic toggle
910: .Ic localchars
911: below)
912: and the
913: .Ic quit
914: character is typed, a
915: .Dv TELNET BRK
916: sequence (see
917: .Ic send
918: .Ic brk
919: above)
920: is sent to the remote host.
921: The initial value for the quit character is taken to be
922: the terminal's
923: .Ic quit
924: character.
925: .It Ic reprint
926: If
927: .Nm telnet
928: is operating in
929: .Dv LINEMODE
930: or \*(Lqold line by line\*(Lq mode, then this character is taken to
931: be the terminal's
932: .Ic reprint
933: character.
934: The initial value for the reprint character is taken to be
935: the terminal's
936: .Ic reprint
937: character.
938: .It Ic rlogin
939: This is the rlogin escape character.
940: If set, the normal
941: .Tn TELNET
942: escape character is ignored unless it is
943: preceded by this character at the beginning of a line.
944: This character, at the beginning of a line followed by
945: a "." closes the connection; when followed by a ^Z it
1.5 deraadt 946: suspends the
947: .Nm telnet
948: command. The initial state is to
1.1 deraadt 949: disable the rlogin escape character.
950: .It Ic start
951: If the
952: .Dv TELNET TOGGLE-FLOW-CONTROL
953: option has been enabled,
954: then this character is taken to
955: be the terminal's
956: .Ic start
957: character.
1.5 deraadt 958: The initial value for the start character is taken to be
1.1 deraadt 959: the terminal's
960: .Ic start
961: character.
962: .It Ic stop
963: If the
964: .Dv TELNET TOGGLE-FLOW-CONTROL
965: option has been enabled,
966: then this character is taken to
967: be the terminal's
968: .Ic stop
969: character.
1.5 deraadt 970: The initial value for the stop character is taken to be
1.1 deraadt 971: the terminal's
972: .Ic stop
973: character.
974: .It Ic susp
975: If
976: .Nm telnet
977: is in
978: .Ic localchars
979: mode, or
980: .Dv LINEMODE
981: is enabled, and the
982: .Ic suspend
983: character is typed, a
984: .Dv TELNET SUSP
985: sequence (see
986: .Ic send
987: .Ic susp
988: above)
989: is sent to the remote host.
990: The initial value for the suspend character is taken to be
991: the terminal's
992: .Ic suspend
993: character.
994: .It Ic tracefile
995: This is the file to which the output, caused by
996: .Ic netdata
997: or
998: .Ic option
999: tracing being
1000: .Dv TRUE ,
1001: will be written. If it is set to
1002: .Dq Fl ,
1003: then tracing information will be written to standard output (the default).
1004: .It Ic worderase
1005: If
1006: .Nm telnet
1007: is operating in
1008: .Dv LINEMODE
1009: or \*(Lqold line by line\*(Lq mode, then this character is taken to
1010: be the terminal's
1011: .Ic worderase
1012: character.
1013: The initial value for the worderase character is taken to be
1014: the terminal's
1015: .Ic worderase
1016: character.
1017: .It Ic \&?
1018: Displays the legal
1019: .Ic set
1020: .Pq Ic unset
1021: commands.
1022: .El
1023: .It Ic slc Ar state
1024: The
1025: .Ic slc
1026: command (Set Local Characters) is used to set
1.4 deraadt 1027: or change the state of the special
1.1 deraadt 1028: characters when the
1029: .Dv TELNET LINEMODE
1030: option has
1031: been enabled. Special characters are characters that get
1032: mapped to
1033: .Tn TELNET
1034: commands sequences (like
1035: .Ic ip
1036: or
1037: .Ic quit )
1038: or line editing characters (like
1039: .Ic erase
1040: and
1041: .Ic kill ) .
1042: By default, the local special characters are exported.
1043: .Bl -tag -width Fl
1044: .It Ic check
1045: Verify the current settings for the current special characters.
1046: The remote side is requested to send all the current special
1047: character settings, and if there are any discrepancies with
1048: the local side, the local side will switch to the remote value.
1049: .It Ic export
1050: Switch to the local defaults for the special characters. The
1051: local default characters are those of the local terminal at
1052: the time when
1053: .Nm telnet
1054: was started.
1055: .It Ic import
1056: Switch to the remote defaults for the special characters.
1057: The remote default characters are those of the remote system
1058: at the time when the
1059: .Tn TELNET
1060: connection was established.
1061: .It Ic \&?
1062: Prints out help information for the
1063: .Ic slc
1064: command.
1065: .El
1066: .It Ic status
1067: Show the current status of
1068: .Nm telnet .
1069: This includes the peer one is connected to, as well
1070: as the current mode.
1071: .It Ic toggle Ar arguments ...
1072: Toggle (between
1073: .Dv TRUE
1074: and
1075: .Dv FALSE )
1076: various flags that control how
1077: .Nm telnet
1078: responds to events.
1079: These flags may be set explicitly to
1080: .Dv TRUE
1081: or
1082: .Dv FALSE
1083: using the
1084: .Ic set
1085: and
1086: .Ic unset
1087: commands listed above.
1088: More than one argument may be specified.
1089: The state of these flags may be interrogated with the
1090: .Ic display
1091: command.
1092: Valid arguments are:
1093: .Bl -tag -width Ar
1094: .It Ic authdebug
1095: Turns on debugging information for the authentication code.
1096: .It Ic autoflush
1097: If
1098: .Ic autoflush
1099: and
1100: .Ic localchars
1101: are both
1102: .Dv TRUE ,
1103: then when the
1104: .Ic ao ,
1105: or
1106: .Ic quit
1107: characters are recognized (and transformed into
1108: .Tn TELNET
1109: sequences; see
1110: .Ic set
1111: above for details),
1112: .Nm telnet
1113: refuses to display any data on the user's terminal
1114: until the remote system acknowledges (via a
1115: .Dv TELNET TIMING MARK
1116: option)
1117: that it has processed those
1118: .Tn TELNET
1119: sequences.
1120: The initial value for this toggle is
1121: .Dv TRUE
1122: if the terminal user had not
1123: done an "stty noflsh", otherwise
1124: .Dv FALSE
1125: (see
1126: .Xr stty 1 ) .
1127: .It Ic autodecrypt
1128: When the
1129: .Dv TELNET ENCRYPT
1130: option is negotiated, by
1131: default the actual encryption (decryption) of the data
1132: stream does not start automatically. The autoencrypt
1133: (autodecrypt) command states that encryption of the
1134: output (input) stream should be enabled as soon as
1135: possible.
1136: .Pp
1137: Note: Because of export controls, the
1138: .Dv TELNET ENCRYPT
1139: option is not supported outside the United States and Canada.
1140: .It Ic autologin
1141: If the remote side supports the
1142: .Dv TELNET AUTHENTICATION
1143: option
1144: .Tn TELNET
1145: attempts to use it to perform automatic authentication. If the
1146: .Dv AUTHENTICATION
1147: option is not supported, the user's login
1148: name are propagated through the
1149: .Dv TELNET ENVIRON
1150: option.
1151: This command is the same as specifying
1152: .Ar a
1153: option on the
1154: .Ic open
1155: command.
1156: .It Ic autosynch
1157: If
1158: .Ic autosynch
1159: and
1160: .Ic localchars
1161: are both
1162: .Dv TRUE ,
1163: then when either the
1164: .Ic intr
1165: or
1166: .Ic quit
1167: characters is typed (see
1168: .Ic set
1169: above for descriptions of the
1170: .Ic intr
1171: and
1172: .Ic quit
1173: characters), the resulting
1174: .Tn TELNET
1175: sequence sent is followed by the
1176: .Dv TELNET SYNCH
1177: sequence.
1178: This procedure
1179: .Ic should
1180: cause the remote system to begin throwing away all previously
1181: typed input until both of the
1182: .Tn TELNET
1183: sequences have been read and acted upon.
1184: The initial value of this toggle is
1185: .Dv FALSE .
1186: .It Ic binary
1187: Enable or disable the
1188: .Dv TELNET BINARY
1189: option on both input and output.
1190: .It Ic inbinary
1191: Enable or disable the
1192: .Dv TELNET BINARY
1193: option on input.
1194: .It Ic outbinary
1195: Enable or disable the
1196: .Dv TELNET BINARY
1197: option on output.
1198: .It Ic crlf
1199: If this is
1200: .Dv TRUE ,
1201: then carriage returns will be sent as
1202: .Li <CR><LF> .
1203: If this is
1204: .Dv FALSE ,
1205: then carriage returns will be send as
1206: .Li <CR><NUL> .
1207: The initial value for this toggle is
1208: .Dv FALSE .
1209: .It Ic crmod
1210: Toggle carriage return mode.
1211: When this mode is enabled, most carriage return characters received from
1212: the remote host will be mapped into a carriage return followed by
1213: a line feed.
1214: This mode does not affect those characters typed by the user, only
1215: those received from the remote host.
1216: This mode is not very useful unless the remote host
1217: only sends carriage return, but never line feed.
1218: The initial value for this toggle is
1219: .Dv FALSE .
1220: .It Ic debug
1221: Toggles socket level debugging (useful only to the
1222: .Ic super user ) .
1223: The initial value for this toggle is
1224: .Dv FALSE .
1225: .It Ic encdebug
1226: Turns on debugging information for the encryption code.
1227: .It Ic localchars
1228: If this is
1229: .Dv TRUE ,
1230: then the
1231: .Ic flush ,
1232: .Ic interrupt ,
1233: .Ic quit ,
1234: .Ic erase ,
1235: and
1236: .Ic kill
1237: characters (see
1238: .Ic set
1239: above) are recognized locally, and transformed into (hopefully) appropriate
1240: .Tn TELNET
1241: control sequences
1242: (respectively
1243: .Ic ao ,
1244: .Ic ip ,
1245: .Ic brk ,
1246: .Ic ec ,
1247: and
1248: .Ic el ;
1249: see
1250: .Ic send
1251: above).
1252: The initial value for this toggle is
1253: .Dv TRUE
1254: in \*(Lqold line by line\*(Rq mode,
1255: and
1256: .Dv FALSE
1257: in \*(Lqcharacter at a time\*(Rq mode.
1258: When the
1259: .Dv LINEMODE
1260: option is enabled, the value of
1261: .Ic localchars
1262: is ignored, and assumed to always be
1263: .Dv TRUE .
1264: If
1265: .Dv LINEMODE
1266: has ever been enabled, then
1267: .Ic quit
1268: is sent as
1269: .Ic abort ,
1270: and
1271: .Ic eof and
1.5 deraadt 1272: .Ic suspend
1.1 deraadt 1273: are sent as
1274: .Ic eof and
1.5 deraadt 1275: .Ic susp
1276: (see
1.1 deraadt 1277: .Ic send
1278: above).
1279: .It Ic netdata
1280: Toggles the display of all network data (in hexadecimal format).
1281: The initial value for this toggle is
1282: .Dv FALSE .
1283: .It Ic options
1284: Toggles the display of some internal
1285: .Nm telnet
1286: protocol processing (having to do with
1287: .Tn TELNET
1288: options).
1289: The initial value for this toggle is
1290: .Dv FALSE .
1291: .It Ic prettydump
1292: When the
1293: .Ic netdata
1294: toggle is enabled, if
1295: .Ic prettydump
1296: is enabled the output from the
1297: .Ic netdata
1298: command will be formatted in a more user readable format.
1299: Spaces are put between each character in the output, and the
1300: beginning of any
1301: .Tn TELNET
1302: escape sequence is preceded by a '*' to aid in locating them.
1303: .It Ic skiprc
1304: When the skiprc toggle is
1305: .Dv TRUE ,
1306: .Tn TELNET
1307: skips the reading of the
1308: .Pa \&.telnetrc
1309: file in the users home
1310: directory when connections are opened. The initial
1311: value for this toggle is
1312: .Dv FALSE.
1313: .It Ic termdata
1314: Toggles the display of all terminal data (in hexadecimal format).
1315: The initial value for this toggle is
1316: .Dv FALSE .
1317: .It Ic verbose_encrypt
1318: When the
1319: .Ic verbose_encrypt
1320: toggle is
1321: .Dv TRUE ,
1.5 deraadt 1322: .Nm telnet
1.1 deraadt 1323: prints out a message each time encryption is enabled or
1324: disabled. The initial value for this toggle is
1325: .Dv FALSE.
1326: Note: Because of export controls, data encryption
1327: is not supported outside of the United States and Canada.
1328: .It Ic \&?
1329: Displays the legal
1330: .Ic toggle
1331: commands.
1332: .El
1333: .It Ic z
1334: Suspend
1335: .Nm telnet .
1336: This command only works when the user is using the
1337: .Xr csh 1 .
1338: .It Ic \&! Op Ar command
1339: Execute a single command in a subshell on the local
1340: system. If
1.5 deraadt 1341: .Ar command
1.1 deraadt 1342: is omitted, then an interactive
1343: subshell is invoked.
1344: .It Ic \&? Op Ar command
1345: Get help. With no arguments,
1346: .Nm telnet
1347: prints a help summary.
1348: If a command is specified,
1349: .Nm telnet
1350: will print the help information for just that command.
1351: .El
1352: .Sh ENVIRONMENT
1353: .Nm Telnet
1354: uses at least the
1355: .Ev HOME ,
1356: .Ev SHELL ,
1357: .Ev DISPLAY ,
1358: and
1359: .Ev TERM
1360: environment variables.
1361: Other environment variables may be propagated
1362: to the other side via the
1363: .Dv TELNET ENVIRON
1364: option.
1365: .Sh FILES
1366: .Bl -tag -width ~/.telnetrc -compact
1367: .It Pa ~/.telnetrc
1368: user customized telnet startup values
1369: .El
1370: .Sh HISTORY
1371: The
1372: .Nm Telnet
1373: command appeared in
1374: .Bx 4.2 .
1375: .Sh NOTES
1376: .Pp
1377: On some remote systems, echo has to be turned off manually when in
1378: \*(Lqold line by line\*(Rq mode.
1379: .Pp
1380: In \*(Lqold line by line\*(Rq mode or
1381: .Dv LINEMODE
1382: the terminal's
1383: .Ic eof
1384: character is only recognized (and sent to the remote system)
1385: when it is the first character on a line.
![[BACK]](/icons/back.gif){kind=icon}
Return to telnet.1 CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / telnet