Annotation of src/usr.bin/telnet/telnet.1, Revision 1.10
1.10 ! art 1: .\" $OpenBSD: telnet.1,v 1.9 1997/12/25 00:29:26 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
1.10 ! art 204: Turns on encryption of the data stream if possible.
1.1 deraadt 205: .It Ar host
206: Indicates the official name, an alias, or the Internet address
207: of a remote host.
208: .It Ar port
209: Indicates a port number (address of an application). If a number is
210: not specified, the default
211: .Nm telnet
212: port is used.
213: .El
214: .Pp
215: When in rlogin mode, a line of the form ~. disconnects from the
216: remote host; ~ is the telnet escape character.
217: Similarly, the line ~^Z suspends the telnet session.
218: The line ~^] escapes to the normal telnet escape prompt.
219: .Pp
220: Once a connection has been opened,
221: .Nm telnet
222: will attempt to enable the
223: .Dv TELNET LINEMODE
224: option.
225: If this fails, then
226: .Nm telnet
227: will revert to one of two input modes:
228: either \*(Lqcharacter at a time\*(Rq
229: or \*(Lqold line by line\*(Rq
230: depending on what the remote system supports.
231: .Pp
232: When
233: .Dv LINEMODE
234: is enabled, character processing is done on the
235: local system, under the control of the remote system. When input
236: editing or character echoing is to be disabled, the remote system
237: will relay that information. The remote system will also relay
238: changes to any special characters that happen on the remote
239: system, so that they can take effect on the local system.
240: .Pp
241: In \*(Lqcharacter at a time\*(Rq mode, most
242: text typed is immediately sent to the remote host for processing.
243: .Pp
244: In \*(Lqold line by line\*(Rq mode, all text is echoed locally,
245: and (normally) only completed lines are sent to the remote host.
246: The \*(Lqlocal echo character\*(Rq (initially \*(Lq^E\*(Rq) may be used
247: to turn off and on the local echo
248: (this would mostly be used to enter passwords
249: without the password being echoed).
250: .Pp
251: If the
252: .Dv LINEMODE
253: option is enabled, or if the
254: .Ic localchars
255: toggle is
256: .Dv TRUE
257: (the default for \*(Lqold line by line\*(Lq; see below),
258: the user's
259: .Ic quit ,
260: .Ic intr ,
261: and
262: .Ic flush
263: characters are trapped locally, and sent as
264: .Tn TELNET
265: protocol sequences to the remote side.
266: If
267: .Dv LINEMODE
268: has ever been enabled, then the user's
269: .Ic susp
270: and
271: .Ic eof
272: are also sent as
273: .Tn TELNET
274: protocol sequences,
275: and
276: .Ic quit
277: is sent as a
278: .Dv TELNET ABORT
279: instead of
1.8 deraadt 280: .Dv BREAK .
1.1 deraadt 281: There are options (see
282: .Ic toggle
283: .Ic autoflush
284: and
285: .Ic toggle
286: .Ic autosynch
287: below)
288: which cause this action to flush subsequent output to the terminal
289: (until the remote host acknowledges the
290: .Tn TELNET
291: sequence) and flush previous terminal input
292: (in the case of
293: .Ic quit
294: and
295: .Ic intr ) .
296: .Pp
297: While connected to a remote host,
298: .Nm telnet
299: command mode may be entered by typing the
300: .Nm telnet
301: \*(Lqescape character\*(Rq (initially \*(Lq^]\*(Rq).
302: When in command mode, the normal terminal editing conventions are available.
303: .Pp
304: The following
305: .Nm telnet
306: commands are available.
307: Only enough of each command to uniquely identify it need be typed
308: (this is also true for arguments to the
309: .Ic mode ,
310: .Ic set ,
311: .Ic toggle ,
312: .Ic unset ,
313: .Ic slc ,
314: .Ic environ ,
315: and
316: .Ic display
317: commands).
318: .Pp
319: .Bl -tag -width "mode type"
320: .It Ic auth Ar argument ...
321: The auth command manipulates the information sent through the
322: .Dv TELNET AUTHENTICATE
323: option. Valid arguments for the
324: auth command are as follows:
325: .Bl -tag -width "disable type"
326: .It Ic disable Ar type
327: Disables the specified type of authentication. To
328: obtain a list of available types, use the
329: .Ic auth disable \&?
330: command.
331: .It Ic enable Ar type
332: Enables the specified type of authentication. To
333: obtain a list of available types, use the
334: .Ic auth enable \&?
335: command.
336: .It Ic status
337: Lists the current status of the various types of
338: authentication.
339: .El
340: .It Ic close
341: Close a
342: .Tn TELNET
343: session and return to command mode.
344: .It Ic display Ar argument ...
345: Displays all, or some, of the
346: .Ic set
347: and
348: .Ic toggle
349: values (see below).
350: .It Ic encrypt Ar argument ...
351: The encrypt command manipulates the information sent through the
352: .Dv TELNET ENCRYPT
353: option.
1.10 ! art 354: ..Pp
1.1 deraadt 355: Valid arguments for the encrypt command are as follows:
356: .Bl -tag -width Ar
357: .It Ic disable Ar type Ic [input|output]
358: Disables the specified type of encryption. If you
359: omit the input and output, both input and output
360: are disabled. To obtain a list of available
361: types, use the
362: .Ic encrypt disable \&?
363: command.
364: .It Ic enable Ar type Ic [input|output]
365: Enables the specified type of encryption. If you
366: omit input and output, both input and output are
367: enabled. To obtain a list of available types, use the
368: .Ic encrypt enable \&?
369: command.
370: .It Ic input
371: This is the same as the
372: .Ic encrypt start input
373: command.
374: .It Ic -input
375: This is the same as the
376: .Ic encrypt stop input
377: command.
378: .It Ic output
379: This is the same as the
380: .Ic encrypt start output
381: command.
382: .It Ic -output
383: This is the same as the
384: .Ic encrypt stop output
385: command.
386: .It Ic start Ic [input|output]
387: Attempts to start encryption. If you omit
388: .Ic input
389: and
390: .Ic output,
391: both input and output are enabled. To
392: obtain a list of available types, use the
393: .Ic encrypt enable \&?
394: command.
395: .It Ic status
396: Lists the current status of encryption.
397: .It Ic stop Ic [input|output]
398: Stops encryption. If you omit input and output,
399: encryption is on both input and output.
400: .It Ic type Ar type
401: Sets the default type of encryption to be used
402: with later
403: .Ic encrypt start
404: or
405: .Ic encrypt stop
406: commands.
407: .El
408: .It Ic environ Ar arguments...
409: The
410: .Ic environ
411: command is used to manipulate the
1.8 deraadt 412: the variables that may be sent through the
1.1 deraadt 413: .Dv TELNET ENVIRON
414: option.
415: The initial set of variables is taken from the users
416: environment, with only the
417: .Ev DISPLAY
418: and
419: .Ev PRINTER
420: variables being exported by default.
421: The
422: .Ev USER
423: variable is also exported if the
424: .Fl a
425: or
426: .Fl l
427: options are used.
428: .br
429: Valid arguments for the
430: .Ic environ
431: command are:
432: .Bl -tag -width Fl
433: .It Ic define Ar variable value
434: Define the variable
435: .Ar variable
436: to have a value of
437: .Ar value.
438: Any variables defined by this command are automatically exported.
439: The
440: .Ar value
441: may be enclosed in single or double quotes so
442: that tabs and spaces may be included.
443: .It Ic undefine Ar variable
444: Remove
445: .Ar variable
446: from the list of environment variables.
447: .It Ic export Ar variable
448: Mark the variable
449: .Ar variable
450: to be exported to the remote side.
451: .It Ic unexport Ar variable
452: Mark the variable
453: .Ar variable
454: to not be exported unless
455: explicitly asked for by the remote side.
456: .It Ic list
457: List the current set of environment variables.
458: Those marked with a
459: .Cm *
460: will be sent automatically,
461: other variables will only be sent if explicitly requested.
462: .It Ic \&?
463: Prints out help information for the
464: .Ic environ
465: command.
466: .El
467: .It Ic logout
468: Sends the
469: .Dv TELNET LOGOUT
470: option to the remote side.
471: This command is similar to a
472: .Ic close
473: command; however, if the remote side does not support the
474: .Dv LOGOUT
475: option, nothing happens.
476: If, however, the remote side does support the
477: .Dv LOGOUT
478: option, this command should cause the remote side to close the
479: .Tn TELNET
480: connection.
481: If the remote side also supports the concept of
482: suspending a user's session for later reattachment,
483: the logout argument indicates that you
484: should terminate the session immediately.
485: .It Ic mode Ar type
486: .Ar Type
487: is one of several options, depending on the state of the
488: .Tn TELNET
489: session.
490: The remote host is asked for permission to go into the requested mode.
491: If the remote host is capable of entering that mode, the requested
492: mode will be entered.
493: .Bl -tag -width Ar
494: .It Ic character
495: Disable the
496: .Dv TELNET LINEMODE
497: option, or, if the remote side does not understand the
498: .Dv LINEMODE
499: option, then enter \*(Lqcharacter at a time\*(Lq mode.
500: .It Ic line
501: Enable the
502: .Dv TELNET LINEMODE
503: option, or, if the remote side does not understand the
504: .Dv LINEMODE
505: option, then attempt to enter \*(Lqold-line-by-line\*(Lq mode.
506: .It Ic isig Pq Ic \-isig
507: Attempt to enable (disable) the
508: .Dv TRAPSIG
509: mode of the
510: .Dv LINEMODE
511: option.
512: This requires that the
513: .Dv LINEMODE
514: option be enabled.
515: .It Ic edit Pq Ic \-edit
516: Attempt to enable (disable) the
517: .Dv EDIT
518: mode of the
519: .Dv LINEMODE
520: option.
521: This requires that the
522: .Dv LINEMODE
523: option be enabled.
524: .It Ic softtabs Pq Ic \-softtabs
525: Attempt to enable (disable) the
526: .Dv SOFT_TAB
527: mode of the
528: .Dv LINEMODE
529: option.
530: This requires that the
531: .Dv LINEMODE
532: option be enabled.
533: .It Ic litecho Pq Ic \-litecho
534: Attempt to enable (disable) the
535: .Dv LIT_ECHO
536: mode of the
537: .Dv LINEMODE
538: option.
539: This requires that the
540: .Dv LINEMODE
541: option be enabled.
542: .It Ic \&?
543: Prints out help information for the
544: .Ic mode
545: command.
546: .El
547: .It Xo
548: .Ic open Ar host
1.5 deraadt 549: .Op Fl l Ar user
550: .Oo Op Fl
1.1 deraadt 551: .Ar port Oc
552: .Xc
553: Open a connection to the named host.
554: If no port number
555: is specified,
556: .Nm telnet
557: will attempt to contact a
558: .Tn TELNET
559: server at the default port.
560: The host specification may be either a host name (see
1.7 deraadt 561: .Xr hosts 5 )
1.1 deraadt 562: or an Internet address specified in the \*(Lqdot notation\*(Rq (see
563: .Xr inet 3 ) .
564: The
1.5 deraadt 565: .Fl l
1.1 deraadt 566: option may be used to specify the user name
567: to be passed to the remote system via the
568: .Ev ENVIRON
569: option.
570: When connecting to a non-standard port,
571: .Nm telnet
572: omits any automatic initiation of
573: .Tn TELNET
574: options. When the port number is preceded by a minus sign,
575: the initial option negotiation is done.
576: After establishing a connection, the file
577: .Pa \&.telnetrc
578: in the
1.7 deraadt 579: user's home directory is opened. Lines beginning with a # are
1.1 deraadt 580: comment lines. Blank lines are ignored. Lines that begin
581: without white space are the start of a machine entry. The
582: first thing on the line is the name of the machine that is
583: being connected to. The rest of the line, and successive
584: lines that begin with white space are assumed to be
585: .Nm telnet
586: commands and are processed as if they had been typed
587: in manually to the
588: .Nm telnet
589: command prompt.
590: .It Ic quit
591: Close any open
592: .Tn TELNET
593: session and exit
594: .Nm telnet .
595: An end of file (in command mode) will also close a session and exit.
596: .It Ic send Ar arguments
597: Sends one or more special character sequences to the remote host.
598: The following are the arguments which may be specified
599: (more than one argument may be specified at a time):
600: .Pp
601: .Bl -tag -width escape
602: .It Ic abort
603: Sends the
604: .Dv TELNET ABORT
605: (Abort
606: processes)
607: sequence.
608: .It Ic ao
609: Sends the
610: .Dv TELNET AO
611: (Abort Output) sequence, which should cause the remote system to flush
612: all output
613: .Em from
614: the remote system
615: .Em to
616: the user's terminal.
617: .It Ic ayt
618: Sends the
619: .Dv TELNET AYT
620: (Are You There)
621: sequence, to which the remote system may or may not choose to respond.
622: .It Ic brk
623: Sends the
624: .Dv TELNET BRK
625: (Break) sequence, which may have significance to the remote
626: system.
627: .It Ic ec
628: Sends the
629: .Dv TELNET EC
630: (Erase Character)
631: sequence, which should cause the remote system to erase the last character
632: entered.
633: .It Ic el
634: Sends the
635: .Dv TELNET EL
636: (Erase Line)
637: sequence, which should cause the remote system to erase the line currently
638: being entered.
639: .It Ic eof
640: Sends the
641: .Dv TELNET EOF
642: (End Of File)
643: sequence.
644: .It Ic eor
645: Sends the
646: .Dv TELNET EOR
647: (End of Record)
648: sequence.
649: .It Ic escape
650: Sends the current
651: .Nm telnet
652: escape character (initially \*(Lq^\*(Rq).
653: .It Ic ga
654: Sends the
655: .Dv TELNET GA
656: (Go Ahead)
657: sequence, which likely has no significance to the remote system.
658: .It Ic getstatus
659: If the remote side supports the
660: .Dv TELNET STATUS
661: command,
662: .Ic getstatus
663: will send the subnegotiation to request that the server send
664: its current option status.
665: .It Ic ip
666: Sends the
667: .Dv TELNET IP
668: (Interrupt Process) sequence, which should cause the remote
669: system to abort the currently running process.
670: .It Ic nop
671: Sends the
672: .Dv TELNET NOP
673: (No OPeration)
674: sequence.
675: .It Ic susp
676: Sends the
677: .Dv TELNET SUSP
678: (SUSPend process)
679: sequence.
680: .It Ic synch
681: Sends the
682: .Dv TELNET SYNCH
683: sequence.
684: This sequence causes the remote system to discard all previously typed
685: (but not yet read) input.
686: This sequence is sent as
687: .Tn TCP
688: urgent
689: data (and may not work if the remote system is a
690: .Bx 4.2
691: system -- if
692: it doesn't work, a lower case \*(Lqr\*(Rq may be echoed on the terminal).
693: .It Ic do Ar cmd
694: .It Ic dont Ar cmd
695: .It Ic will Ar cmd
696: .It Ic wont Ar cmd
697: Sends the
698: .Dv TELNET DO
699: .Ar cmd
700: sequence.
701: .Ar Cmd
702: can be either a decimal number between 0 and 255,
703: or a symbolic name for a specific
704: .Dv TELNET
705: command.
706: .Ar Cmd
707: can also be either
708: .Ic help
709: or
710: .Ic \&?
711: to print out help information, including
712: a list of known symbolic names.
713: .It Ic \&?
714: Prints out help information for the
715: .Ic send
716: command.
717: .El
718: .It Ic set Ar argument value
719: .It Ic unset Ar argument value
720: The
721: .Ic set
722: command will set any one of a number of
723: .Nm telnet
724: variables to a specific value or to
725: .Dv TRUE .
726: The special value
727: .Ic off
728: turns off the function associated with
729: the variable, this is equivalent to using the
730: .Ic unset
731: command.
732: The
733: .Ic unset
734: command will disable or set to
735: .Dv FALSE
736: any of the specified functions.
737: The values of variables may be interrogated with the
738: .Ic display
739: command.
740: The variables which may be set or unset, but not toggled, are
741: listed here. In addition, any of the variables for the
742: .Ic toggle
743: command may be explicitly set or unset using
744: the
745: .Ic set
746: and
747: .Ic unset
748: commands.
749: .Bl -tag -width escape
750: .It Ic ayt
751: If
752: .Tn TELNET
753: is in localchars mode, or
754: .Dv LINEMODE
755: is enabled, and the status character is typed, a
756: .Dv TELNET AYT
757: sequence (see
758: .Ic send ayt
759: preceding) is sent to the
760: remote host. The initial value for the "Are You There"
761: character is the terminal's status character.
762: .It Ic echo
763: This is the value (initially \*(Lq^E\*(Rq) which, when in
764: \*(Lqline by line\*(Rq mode, toggles between doing local echoing
765: of entered characters (for normal processing), and suppressing
766: echoing of entered characters (for entering, say, a password).
767: .It Ic eof
768: If
769: .Nm telnet
770: is operating in
771: .Dv LINEMODE
772: or \*(Lqold line by line\*(Rq mode, entering this character
773: as the first character on a line will cause this character to be
774: sent to the remote system.
775: The initial value of the eof character is taken to be the terminal's
776: .Ic eof
777: character.
778: .It Ic erase
779: If
780: .Nm telnet
781: is in
782: .Ic localchars
783: mode (see
784: .Ic toggle
785: .Ic localchars
786: below),
787: .Sy and
788: if
789: .Nm telnet
790: is operating in \*(Lqcharacter at a time\*(Rq mode, then when this
791: character is typed, a
792: .Dv TELNET EC
793: sequence (see
794: .Ic send
795: .Ic ec
796: above)
797: is sent to the remote system.
798: The initial value for the erase character is taken to be
799: the terminal's
800: .Ic erase
801: character.
802: .It Ic escape
803: This is the
804: .Nm telnet
805: escape character (initially \*(Lq^[\*(Rq) which causes entry
806: into
807: .Nm telnet
808: command mode (when connected to a remote system).
809: .It Ic flushoutput
810: If
811: .Nm telnet
812: is in
813: .Ic localchars
814: mode (see
815: .Ic toggle
816: .Ic localchars
817: below)
818: and the
819: .Ic flushoutput
820: character is typed, a
821: .Dv TELNET AO
822: sequence (see
823: .Ic send
824: .Ic ao
825: above)
826: is sent to the remote host.
827: The initial value for the flush character is taken to be
828: the terminal's
829: .Ic flush
830: character.
831: .It Ic forw1
832: .It Ic forw2
833: If
834: .Tn TELNET
835: is operating in
836: .Dv LINEMODE ,
837: these are the
838: characters that, when typed, cause partial lines to be
839: forwarded to the remote system. The initial value for
840: the forwarding characters are taken from the terminal's
841: eol and eol2 characters.
842: .It Ic interrupt
843: If
844: .Nm telnet
845: is in
846: .Ic localchars
847: mode (see
848: .Ic toggle
849: .Ic localchars
850: below)
851: and the
852: .Ic interrupt
853: character is typed, a
854: .Dv TELNET IP
855: sequence (see
856: .Ic send
857: .Ic ip
858: above)
859: is sent to the remote host.
860: The initial value for the interrupt character is taken to be
861: the terminal's
862: .Ic intr
863: character.
864: .It Ic kill
865: If
866: .Nm telnet
867: is in
868: .Ic localchars
869: mode (see
870: .Ic toggle
871: .Ic localchars
872: below),
873: .Ic and
874: if
875: .Nm telnet
876: is operating in \*(Lqcharacter at a time\*(Rq mode, then when this
877: character is typed, a
878: .Dv TELNET EL
879: sequence (see
880: .Ic send
881: .Ic el
882: above)
883: is sent to the remote system.
884: The initial value for the kill character is taken to be
885: the terminal's
886: .Ic kill
887: character.
888: .It Ic lnext
889: If
890: .Nm telnet
891: is operating in
892: .Dv LINEMODE
893: or \*(Lqold line by line\*(Lq mode, then this character is taken to
894: be the terminal's
895: .Ic lnext
896: character.
897: The initial value for the lnext character is taken to be
898: the terminal's
899: .Ic lnext
900: character.
901: .It Ic quit
902: If
903: .Nm telnet
904: is in
905: .Ic localchars
906: mode (see
907: .Ic toggle
908: .Ic localchars
909: below)
910: and the
911: .Ic quit
912: character is typed, a
913: .Dv TELNET BRK
914: sequence (see
915: .Ic send
916: .Ic brk
917: above)
918: is sent to the remote host.
919: The initial value for the quit character is taken to be
920: the terminal's
921: .Ic quit
922: character.
923: .It Ic reprint
924: If
925: .Nm telnet
926: is operating in
927: .Dv LINEMODE
928: or \*(Lqold line by line\*(Lq mode, then this character is taken to
929: be the terminal's
930: .Ic reprint
931: character.
932: The initial value for the reprint character is taken to be
933: the terminal's
934: .Ic reprint
935: character.
936: .It Ic rlogin
937: This is the rlogin escape character.
938: If set, the normal
939: .Tn TELNET
940: escape character is ignored unless it is
941: preceded by this character at the beginning of a line.
942: This character, at the beginning of a line followed by
943: a "." closes the connection; when followed by a ^Z it
1.5 deraadt 944: suspends the
945: .Nm telnet
946: command. The initial state is to
1.1 deraadt 947: disable the rlogin escape character.
948: .It Ic start
949: If the
950: .Dv TELNET TOGGLE-FLOW-CONTROL
951: option has been enabled,
952: then this character is taken to
953: be the terminal's
954: .Ic start
955: character.
1.5 deraadt 956: The initial value for the start character is taken to be
1.1 deraadt 957: the terminal's
958: .Ic start
959: character.
960: .It Ic stop
961: If the
962: .Dv TELNET TOGGLE-FLOW-CONTROL
963: option has been enabled,
964: then this character is taken to
965: be the terminal's
966: .Ic stop
967: character.
1.5 deraadt 968: The initial value for the stop character is taken to be
1.1 deraadt 969: the terminal's
970: .Ic stop
971: character.
972: .It Ic susp
973: If
974: .Nm telnet
975: is in
976: .Ic localchars
977: mode, or
978: .Dv LINEMODE
979: is enabled, and the
980: .Ic suspend
981: character is typed, a
982: .Dv TELNET SUSP
983: sequence (see
984: .Ic send
985: .Ic susp
986: above)
987: is sent to the remote host.
988: The initial value for the suspend character is taken to be
989: the terminal's
990: .Ic suspend
991: character.
992: .It Ic tracefile
993: This is the file to which the output, caused by
994: .Ic netdata
995: or
996: .Ic option
997: tracing being
998: .Dv TRUE ,
999: will be written. If it is set to
1000: .Dq Fl ,
1001: then tracing information will be written to standard output (the default).
1002: .It Ic worderase
1003: If
1004: .Nm telnet
1005: is operating in
1006: .Dv LINEMODE
1007: or \*(Lqold line by line\*(Lq mode, then this character is taken to
1008: be the terminal's
1009: .Ic worderase
1010: character.
1011: The initial value for the worderase character is taken to be
1012: the terminal's
1013: .Ic worderase
1014: character.
1015: .It Ic \&?
1016: Displays the legal
1017: .Ic set
1018: .Pq Ic unset
1019: commands.
1020: .El
1021: .It Ic slc Ar state
1022: The
1023: .Ic slc
1024: command (Set Local Characters) is used to set
1.4 deraadt 1025: or change the state of the special
1.1 deraadt 1026: characters when the
1027: .Dv TELNET LINEMODE
1028: option has
1029: been enabled. Special characters are characters that get
1030: mapped to
1031: .Tn TELNET
1032: commands sequences (like
1033: .Ic ip
1034: or
1035: .Ic quit )
1036: or line editing characters (like
1037: .Ic erase
1038: and
1039: .Ic kill ) .
1040: By default, the local special characters are exported.
1041: .Bl -tag -width Fl
1042: .It Ic check
1043: Verify the current settings for the current special characters.
1044: The remote side is requested to send all the current special
1045: character settings, and if there are any discrepancies with
1046: the local side, the local side will switch to the remote value.
1047: .It Ic export
1048: Switch to the local defaults for the special characters. The
1049: local default characters are those of the local terminal at
1050: the time when
1051: .Nm telnet
1052: was started.
1053: .It Ic import
1054: Switch to the remote defaults for the special characters.
1055: The remote default characters are those of the remote system
1056: at the time when the
1057: .Tn TELNET
1058: connection was established.
1059: .It Ic \&?
1060: Prints out help information for the
1061: .Ic slc
1062: command.
1063: .El
1064: .It Ic status
1065: Show the current status of
1066: .Nm telnet .
1067: This includes the peer one is connected to, as well
1068: as the current mode.
1069: .It Ic toggle Ar arguments ...
1070: Toggle (between
1071: .Dv TRUE
1072: and
1073: .Dv FALSE )
1074: various flags that control how
1075: .Nm telnet
1076: responds to events.
1077: These flags may be set explicitly to
1078: .Dv TRUE
1079: or
1080: .Dv FALSE
1081: using the
1082: .Ic set
1083: and
1084: .Ic unset
1085: commands listed above.
1086: More than one argument may be specified.
1087: The state of these flags may be interrogated with the
1088: .Ic display
1089: command.
1090: Valid arguments are:
1091: .Bl -tag -width Ar
1092: .It Ic authdebug
1093: Turns on debugging information for the authentication code.
1094: .It Ic autoflush
1095: If
1096: .Ic autoflush
1097: and
1098: .Ic localchars
1099: are both
1100: .Dv TRUE ,
1101: then when the
1102: .Ic ao ,
1103: or
1104: .Ic quit
1105: characters are recognized (and transformed into
1106: .Tn TELNET
1107: sequences; see
1108: .Ic set
1109: above for details),
1110: .Nm telnet
1111: refuses to display any data on the user's terminal
1112: until the remote system acknowledges (via a
1113: .Dv TELNET TIMING MARK
1114: option)
1115: that it has processed those
1116: .Tn TELNET
1117: sequences.
1118: The initial value for this toggle is
1119: .Dv TRUE
1120: if the terminal user had not
1121: done an "stty noflsh", otherwise
1122: .Dv FALSE
1123: (see
1124: .Xr stty 1 ) .
1125: .It Ic autodecrypt
1126: When the
1127: .Dv TELNET ENCRYPT
1128: option is negotiated, by
1129: default the actual encryption (decryption) of the data
1130: stream does not start automatically. The autoencrypt
1131: (autodecrypt) command states that encryption of the
1132: output (input) stream should be enabled as soon as
1133: possible.
1134: .Pp
1135: .It Ic autologin
1136: If the remote side supports the
1137: .Dv TELNET AUTHENTICATION
1138: option
1139: .Tn TELNET
1140: attempts to use it to perform automatic authentication. If the
1141: .Dv AUTHENTICATION
1142: option is not supported, the user's login
1143: name are propagated through the
1144: .Dv TELNET ENVIRON
1145: option.
1146: This command is the same as specifying
1147: .Ar a
1148: option on the
1149: .Ic open
1150: command.
1151: .It Ic autosynch
1152: If
1153: .Ic autosynch
1154: and
1155: .Ic localchars
1156: are both
1157: .Dv TRUE ,
1158: then when either the
1159: .Ic intr
1160: or
1161: .Ic quit
1162: characters is typed (see
1163: .Ic set
1164: above for descriptions of the
1165: .Ic intr
1166: and
1167: .Ic quit
1168: characters), the resulting
1169: .Tn TELNET
1170: sequence sent is followed by the
1171: .Dv TELNET SYNCH
1172: sequence.
1173: This procedure
1174: .Ic should
1175: cause the remote system to begin throwing away all previously
1176: typed input until both of the
1177: .Tn TELNET
1178: sequences have been read and acted upon.
1179: The initial value of this toggle is
1180: .Dv FALSE .
1181: .It Ic binary
1182: Enable or disable the
1183: .Dv TELNET BINARY
1184: option on both input and output.
1185: .It Ic inbinary
1186: Enable or disable the
1187: .Dv TELNET BINARY
1188: option on input.
1189: .It Ic outbinary
1190: Enable or disable the
1191: .Dv TELNET BINARY
1192: option on output.
1193: .It Ic crlf
1194: If this is
1195: .Dv TRUE ,
1196: then carriage returns will be sent as
1197: .Li <CR><LF> .
1198: If this is
1199: .Dv FALSE ,
1200: then carriage returns will be send as
1201: .Li <CR><NUL> .
1202: The initial value for this toggle is
1203: .Dv FALSE .
1204: .It Ic crmod
1205: Toggle carriage return mode.
1206: When this mode is enabled, most carriage return characters received from
1207: the remote host will be mapped into a carriage return followed by
1208: a line feed.
1209: This mode does not affect those characters typed by the user, only
1210: those received from the remote host.
1211: This mode is not very useful unless the remote host
1212: only sends carriage return, but never line feed.
1213: The initial value for this toggle is
1214: .Dv FALSE .
1215: .It Ic debug
1216: Toggles socket level debugging (useful only to the
1217: .Ic super user ) .
1218: The initial value for this toggle is
1219: .Dv FALSE .
1220: .It Ic encdebug
1221: Turns on debugging information for the encryption code.
1222: .It Ic localchars
1223: If this is
1224: .Dv TRUE ,
1225: then the
1226: .Ic flush ,
1227: .Ic interrupt ,
1228: .Ic quit ,
1229: .Ic erase ,
1230: and
1231: .Ic kill
1232: characters (see
1233: .Ic set
1234: above) are recognized locally, and transformed into (hopefully) appropriate
1235: .Tn TELNET
1236: control sequences
1237: (respectively
1238: .Ic ao ,
1239: .Ic ip ,
1240: .Ic brk ,
1241: .Ic ec ,
1242: and
1243: .Ic el ;
1244: see
1245: .Ic send
1246: above).
1247: The initial value for this toggle is
1248: .Dv TRUE
1249: in \*(Lqold line by line\*(Rq mode,
1250: and
1251: .Dv FALSE
1252: in \*(Lqcharacter at a time\*(Rq mode.
1253: When the
1254: .Dv LINEMODE
1255: option is enabled, the value of
1256: .Ic localchars
1257: is ignored, and assumed to always be
1258: .Dv TRUE .
1259: If
1260: .Dv LINEMODE
1261: has ever been enabled, then
1262: .Ic quit
1263: is sent as
1264: .Ic abort ,
1265: and
1266: .Ic eof and
1.5 deraadt 1267: .Ic suspend
1.1 deraadt 1268: are sent as
1269: .Ic eof and
1.5 deraadt 1270: .Ic susp
1271: (see
1.1 deraadt 1272: .Ic send
1273: above).
1274: .It Ic netdata
1275: Toggles the display of all network data (in hexadecimal format).
1276: The initial value for this toggle is
1277: .Dv FALSE .
1278: .It Ic options
1279: Toggles the display of some internal
1280: .Nm telnet
1281: protocol processing (having to do with
1282: .Tn TELNET
1283: options).
1284: The initial value for this toggle is
1285: .Dv FALSE .
1286: .It Ic prettydump
1287: When the
1288: .Ic netdata
1289: toggle is enabled, if
1290: .Ic prettydump
1291: is enabled the output from the
1292: .Ic netdata
1293: command will be formatted in a more user readable format.
1294: Spaces are put between each character in the output, and the
1295: beginning of any
1296: .Tn TELNET
1297: escape sequence is preceded by a '*' to aid in locating them.
1298: .It Ic skiprc
1299: When the skiprc toggle is
1300: .Dv TRUE ,
1301: .Tn TELNET
1302: skips the reading of the
1303: .Pa \&.telnetrc
1304: file in the users home
1305: directory when connections are opened. The initial
1306: value for this toggle is
1307: .Dv FALSE.
1308: .It Ic termdata
1309: Toggles the display of all terminal data (in hexadecimal format).
1310: The initial value for this toggle is
1311: .Dv FALSE .
1312: .It Ic verbose_encrypt
1313: When the
1314: .Ic verbose_encrypt
1315: toggle is
1316: .Dv TRUE ,
1.5 deraadt 1317: .Nm telnet
1.1 deraadt 1318: prints out a message each time encryption is enabled or
1319: disabled. The initial value for this toggle is
1320: .Dv FALSE.
1321: .It Ic \&?
1322: Displays the legal
1323: .Ic toggle
1324: commands.
1325: .El
1326: .It Ic z
1327: Suspend
1328: .Nm telnet .
1329: This command only works when the user is using the
1330: .Xr csh 1 .
1331: .It Ic \&! Op Ar command
1332: Execute a single command in a subshell on the local
1333: system. If
1.5 deraadt 1334: .Ar command
1.1 deraadt 1335: is omitted, then an interactive
1336: subshell is invoked.
1337: .It Ic \&? Op Ar command
1338: Get help. With no arguments,
1339: .Nm telnet
1340: prints a help summary.
1341: If a command is specified,
1342: .Nm telnet
1343: will print the help information for just that command.
1344: .El
1345: .Sh ENVIRONMENT
1346: .Nm Telnet
1347: uses at least the
1348: .Ev HOME ,
1349: .Ev SHELL ,
1350: .Ev DISPLAY ,
1351: and
1352: .Ev TERM
1353: environment variables.
1354: Other environment variables may be propagated
1355: to the other side via the
1356: .Dv TELNET ENVIRON
1357: option.
1358: .Sh FILES
1359: .Bl -tag -width ~/.telnetrc -compact
1360: .It Pa ~/.telnetrc
1361: user customized telnet startup values
1362: .El
1363: .Sh HISTORY
1364: The
1365: .Nm Telnet
1366: command appeared in
1367: .Bx 4.2 .
1368: .Sh NOTES
1369: .Pp
1370: On some remote systems, echo has to be turned off manually when in
1371: \*(Lqold line by line\*(Rq mode.
1372: .Pp
1373: In \*(Lqold line by line\*(Rq mode or
1374: .Dv LINEMODE
1375: the terminal's
1376: .Ic eof
1377: character is only recognized (and sent to the remote system)
1378: when it is the first character on a line.
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