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1 # $FreeBSD: src/usr.bin/telnet/README,v 1.1.1.2.6.1 2001/03/04 09:10:39 kris Exp $
2 # $DragonFly: src/usr.bin/telnet/README,v 1.2 2003/06/17 04:29:32 dillon Exp $
4 This is a distribution of both client and server telnet. These programs
5 have been compiled on:
6 telnet telnetd
7 4.4 BSD-Lite x x
8 4.3 BSD Reno X X
9 UNICOS 9.1 X X
10 UNICOS 9.0 X X
11 UNICOS 8.0 X X
12 BSDI 2.0 X X
13 Solaris 2.4 x x (no linemode in server)
14 SunOs 4.1.4 X X (no linemode in server)
15 Ultrix 4.3 X X (no linemode in server)
16 Ultrix 4.1 X X (no linemode in server)
18 In addition, previous versions have been compiled on the following
19 machines, but were not available for testing this version.
20 telnet telnetd
21 Next1.0 X X
22 UNICOS 8.3 X X
23 UNICOS 7.C X X
24 UNICOS 7.0 X X
25 SunOs 4.0.3c X X (no linemode in server)
26 4.3 BSD X X (no linemode in server)
27 DYNIX V3.0.12 X X (no linemode in server)
28 Ultrix 3.1 X X (no linemode in server)
29 Ultrix 4.0 X X (no linemode in server)
30 SunOs 3.5 X X (no linemode in server)
31 SunOs 4.1.3 X X (no linemode in server)
32 Solaris 2.2 x x (no linemode in server)
33 Solaris 2.3 x x (no linemode in server)
34 BSDI 1.0 X X
35 BSDI 1.1 X X
36 DYNIX V3.0.17.9 X X (no linemode in server)
37 HP-UX 8.0 x x (no linemode in server)
39 This code should work, but there are no guarantees.
41 May 30, 1995
43 This release represents what is on the 4.4BSD-Lite2 release, which
44 should be the final BSD release. I will continue to support of
45 telnet, The code (without encryption) is available via anonymous ftp
46 from ftp.cray.com, in src/telnet/telnet.YY.MM.DD.NE.tar.Z, where
47 YY.MM.DD is replaced with the year, month and day of the release.
48 If you can't find it at one of these places, at some point in the
49 near future information about the latest releases should be available
50 from ftp.borman.com.
52 In addition, the version with the encryption code is available via
53 ftp from net-dist.mit.edu, in the directory /pub/telnet. There
54 is a README file there that gives further information on how
55 to get the distribution.
57 Questions, comments, bug reports and bug fixes can be sent to
58 one of these addresses:
59 dab@borman.com
60 dab@cray.com
61 dab@bsdi.com
63 This release is mainly bug fixes and code cleanup.
65 Replace all calls to bcopy()/bzero() with calls to
66 memmove()/memset() and all calls to index()/rindex()
67 with calls to strchr()/strrchr().
69 Add some missing diagnostics for option tracing
70 to telnetd.
72 Add support for BSDI 2.0 and Solaris 2.4.
74 Add support for UNICOS 8.0
76 Get rid of expanded tabs and trailing white spaces.
78 From Paul Vixie:
79 Fix for telnet going into an endless spin
80 when the session dies abnormally.
82 From Jef Poskanzer:
83 Changes to allow telnet to compile
84 under SunOS 3.5.
86 From Philip Guenther:
87 makeutx() doesn't expand utmpx,
88 use pututxline() instead.
90 From Chris Torek:
91 Add a sleep(1) before execing login
92 to avoid race condition that can eat
93 up the login prompt.
94 Use terminal speed directly if it is
95 not an encoded value.
97 From Steve Parker:
98 Fix to realloc() call. Fix for execing
99 login on solaris with no user name.
101 January 19, 1994
103 This is a list of some of the changes since the last tar release
104 of telnet/telnetd. There are probably other changes that aren't
105 listed here, but this should hit a lot of the main ones.
107 General:
108 Changed #define for AUTHENTICATE to AUTHENTICATION
109 Changed #define for ENCRYPT to ENCRYPTION
110 Changed #define for DES_ENCRYPT to DES_ENCRYPTION
112 Added support for SPX authentication: -DSPX
114 Added support for Kerberos Version 5 authentication: -DKRB5
116 Added support for ANSI C function prototypes
118 Added support for the NEW-ENVIRON option (RFC-1572)
119 including support for USERVAR.
121 Made support for the old Environment Option (RFC-1408)
122 conditional on -DOLD_ENVIRON
124 Added #define ENV_HACK - support for RFC 1571
126 The encryption code is removed from the public distributions.
127 Domestic 4.4 BSD distributions contain the encryption code.
129 ENV_HACK: Code to deal with systems that only implement
130 the old ENVIRON option, and have reversed definitions
131 of ENV_VAR and ENV_VAL. Also fixes ENV processing in
132 client to handle things besides just the default set...
134 NO_BSD_SETJMP: UNICOS configuration for
135 UNICOS 6.1/6.0/5.1/5.0 systems.
137 STREAMSPTY: Use /dev/ptmx to get a clean pty. This
138 is for SVr4 derivatives (Like Solaris)
140 UTMPX: For systems that have /etc/utmpx. This is for
141 SVr4 derivatives (Like Solaris)
143 Definitions for BSDI 1.0
145 Definitions for 4.3 Reno and 4.4 BSD.
147 Definitions for UNICOS 8.0 and UNICOS 7.C
149 Definitions for Solaris 2.0
151 Definitions for HP-UX 8.0
153 Latest Copyright notices from Berkeley.
155 FLOW-CONTROL: support for RFC-XXXx
158 Client Specific:
160 Fix the "send" command to not send garbage...
162 Fix status message for "skiprc"
164 Make sure to send NAWS after telnet has been suspended
165 or an external command has been run, if the window size
166 has changed.
168 sysV88 support.
170 Server Specific:
172 Support flowcontrol option in non-linemode servers.
174 -k Server supports Kludge Linemode, but will default to
175 either single character mode or real Linemode support.
176 The user will have to explicitly ask to switch into
177 kludge linemode. ("stty extproc", or escape back to
178 to telnet and say "mode line".)
180 -u Specify the length of the hostname field in the utmp
181 file. Hostname longer than this length will be put
182 into the utmp file in dotted decimal notation, rather
183 than putting in a truncated hostname.
185 -U Registered hosts only. If a reverse hostname lookup
186 fails, the connection will be refused.
188 -f/-F
189 Allows forwarding of credentials for KRB5.
191 Februrary 22, 1991:
193 Features:
195 This version of telnet/telnetd has support for both
196 the AUTHENTICATION and ENCRYPTION options. The
197 AUTHENTICATION option is fairly well defined, and
198 an option number has been assigned to it. The
199 ENCRYPTION option is still in a state of flux; an
200 option number has been assigned to, but it is still
201 subject to change. The code is provided in this release
202 for experimental and testing purposes.
204 The telnet "send" command can now be used to send
205 do/dont/will/wont commands, with any telnet option
206 name. The rules for when do/dont/will/wont are sent
207 are still followed, so just because the user requests
208 that one of these be sent doesn't mean that it will
209 be sent...
211 The telnet "getstatus" command no longer requires
212 that option printing be enabled to see the response
213 to the "DO STATUS" command.
215 A -n flag has been added to telnetd to disable
216 keepalives.
218 A new telnet command, "auth" has been added (if
219 AUTHENTICATE is defined). It has four sub-commands,
220 "status", "disable", "enable" and "help".
222 A new telnet command, "encrypt" has been added (if
223 ENCRYPT is defined). It has many sub-commands:
224 "enable", "type", "start", "stop", "input",
225 "-input", "output", "-output", "status", and "help".
227 The LOGOUT option is now supported by both telnet
228 and telnetd, a new command, "logout", was added
229 to support this.
231 Several new toggle options were added:
232 "autoencrypt", "autodecrypt", "autologin", "authdebug",
233 "encdebug", "skiprc", "verbose_encrypt"
235 An "rlogin" interface has been added. If the program
236 is named "rlogin", or the "-r" flag is given, then
237 an rlogin type of interface will be used.
238 ~. Terminates the session
239 ~<susp> Suspend the session
240 ~^] Escape to telnet command mode
241 ~~ Pass through the ~.
242 BUG: If you type the rlogin escape character
243 in the middle of a line while in rlogin
244 mode, you cannot erase it or any characters
245 before it. Hopefully this can be fixed
246 in a future release...
248 General changes:
250 A "libtelnet.a" has now been created. This libraray
251 contains code that is common to both telnet and
252 telnetd. This is also where library routines that
253 are needed, but are not in the standard C library,
254 are placed.
256 The makefiles have been re-done. All of the site
257 specific configuration information has now been put
258 into a single "Config.generic" file, in the top level
259 directory. Changing this one file will take care of
260 all three subdirectories. Also, to add a new/local
261 definition, a "Config.local" file may be created
262 at the top level; if that file exists, the subdirectories
263 will use that file instead of "Config.generic".
265 Many 1-2 line functions in commands.c have been
266 removed, and just inserted in-line, or replaced
267 with a macro.
269 Bug Fixes:
271 The non-termio code in both telnet and telnetd was
272 setting/clearing CTLECH in the sg_flags word. This
273 was incorrect, and has been changed to set/clear the
274 LCTLECH bit in the local mode word.
276 The SRCRT #define has been removed. If IP_OPTIONS
277 and IPPROTO_IP are defined on the system, then the
278 source route code is automatically enabled.
280 The NO_GETTYTAB #define has been removed; there
281 is a compatibility routine that can be built into
282 libtelnet to achive the same results.
284 The server, telnetd, has been switched to use getopt()
285 for parsing the argument list.
287 The code for getting the input/output speeds via
288 cfgetispeed()/cfgetospeed() was still not quite
289 right in telnet. Posix says if the ispeed is 0,
290 then it is really equal to the ospeed.
292 The suboption processing code in telnet now has
293 explicit checks to make sure that we received
294 the entire suboption (telnetd was already doing this).
296 The telnet code for processing the terminal type
297 could cause a core dump if an existing connection
298 was closed, and a new connection opened without
299 exiting telnet.
301 Telnetd was doing a TCSADRAIN when setting the new
302 terminal settings; This is not good, because it means
303 that the tcsetattr() will hang waiting for output to
304 drain, and telnetd is the only one that will drain
305 the output... The fix is to use TCSANOW which does
306 not wait.
308 Telnetd was improperly setting/clearing the ISTRIP
309 flag in the c_lflag field, it should be using the
310 c_iflag field.
312 When the child process of telnetd was opening the
313 slave side of the pty, it was re-setting the EXTPROC
314 bit too early, and some of the other initialization
315 code was wiping it out. This would cause telnetd
316 to go out of linemode and into single character mode.
318 One instance of leaving linemode in telnetd forgot
319 to send a WILL ECHO to the client, the net result
320 would be that the user would see double character
321 echo.
323 If the MODE was being changed several times very
324 quickly, telnetd could get out of sync with the
325 state changes and the returning acks; and wind up
326 being left in the wrong state.
328 September 14, 1990:
330 Switch the client to use getopt() for parsing the
331 argument list. The 4.3Reno getopt.c is included for
332 systems that don't have getopt().
334 Use the posix _POSIX_VDISABLE value for what value
335 to use when disabling special characters. If this
336 is undefined, it defaults to 0x3ff.
338 For non-termio systems, TIOCSETP was being used to
339 change the state of the terminal. This causes the
340 input queue to be flushed, which we don't want. This
341 is now changed to TIOCSETN.
343 Take out the "#ifdef notdef" around the code in the
344 server that generates a "sync" when the pty oputput
345 is flushed. The potential problem is that some older
346 telnet clients may go into an infinate loop when they
347 receive a "sync", if so, the server can be compiled
348 with "NO_URGENT" defined.
350 Fix the client where it was setting/clearing the OPOST
351 bit in the c_lflag field, not the c_oflag field.
353 Fix the client where it was setting/clearing the ISTRIP
354 bit in the c_lflag field, not the c_iflag field. (On
355 4.3Reno, this is the ECHOPRT bit in the c_lflag field.)
356 The client also had its interpretation of WILL BINARY
357 and DO BINARY reversed.
359 Fix a bug in client that would cause a core dump when
360 attempting to remove the last environment variable.
362 In the client, there were a few places were switch()
363 was being passed a character, and if it was a negative
364 value, it could get sign extended, and not match
365 the 8 bit case statements. The fix is to and the
366 switch value with 0xff.
368 Add a couple more printoption() calls in the client, I
369 don't think there are any more places were a telnet
370 command can be received and not printed out when
371 "options" is on.
373 A new flag has been added to the client, "-a". Currently,
374 this just causes the USER name to be sent across, in
375 the future this may be used to signify that automatic
376 authentication is requested.
378 The USER variable is now only sent by the client if
379 the "-a" or "-l user" options are explicity used, or
380 if the user explicitly asks for the "USER" environment
381 variable to be exported. In the server, if it receives
382 the "USER" environment variable, it won't print out the
383 banner message, so that only "Password:" will be printed.
384 This makes the symantics more like rlogin, and should be
385 more familiar to the user. (People are not used to
386 getting a banner message, and then getting just a
387 "Password:" prompt.)
389 Re-vamp the code for starting up the child login
390 process. The code was getting ugly, and it was
391 hard to tell what was really going on. What we
392 do now is after the fork(), in the child:
393 1) make sure we have no controlling tty
394 2) open and initialize the tty
395 3) do a setsid()/setpgrp()
396 4) makes the tty our controlling tty.
397 On some systems, #2 makes the tty our controlling
398 tty, and #4 is a no-op. The parent process does
399 a gets rid of any controlling tty after the child
400 is fork()ed.
402 Use the strdup() library routine in telnet, instead
403 of the local savestr() routine. If you don't have
404 strdup(), you need to define NO_STRDUP.
406 Add support for ^T (SIGINFO/VSTATUS), found in the
407 4.3Reno distribution. This maps to the AYT character.
408 You need a 4-line bugfix in the kernel to get this
409 to work properly:
411 > *** tty_pty.c.ORG Tue Sep 11 09:41:53 1990
412 > --- tty_pty.c Tue Sep 11 17:48:03 1990
413 > ***************
414 > *** 609,613 ****
415 > if ((tp->t_lflag&NOFLSH) == 0)
416 > ttyflush(tp, FREAD|FWRITE);
417 > ! pgsignal(tp->t_pgrp, *(unsigned int *)data);
418 > return(0);
419 > }
420 > --- 609,616 ----
421 > if ((tp->t_lflag&NOFLSH) == 0)
422 > ttyflush(tp, FREAD|FWRITE);
423 > ! pgsignal(tp->t_pgrp, *(unsigned int *)data, 1);
424 > ! if ((*(unsigned int *)data == SIGINFO) &&
425 > ! ((tp->t_lflag&NOKERNINFO) == 0))
426 > ! ttyinfo(tp);
427 > return(0);
428 > }
430 The client is now smarter when setting the telnet escape
431 character; it only sets it to one of VEOL and VEOL2 if
432 one of them is undefined, and the other one is not already
433 defined to the telnet escape character.
435 Handle TERMIOS systems that have separate input and output
436 line speed settings imbedded in the flags.
438 Many other minor bug fixes.
440 June 20, 1990:
441 Re-organize makefiles and source tree. The telnet/Source
442 directory is now gone, and all the source that was in
443 telnet/Source is now just in the telnet directory.
445 Separate makefile for each system are now gone. There
446 are two makefiles, Makefile and Makefile.generic.
447 The "Makefile" has the definitions for the various
448 system, and "Makefile.generic" does all the work.
449 There is a variable called "WHAT" that is used to
450 specify what to make. For example, in the telnet
451 directory, you might say:
452 make 4.4bsd WHAT=clean
453 to clean out the directory.
455 Add support for the ENVIRON and XDISPLOC options.
456 In order for the server to work, login has to have
457 the "-p" option to preserve environment variables.
459 Add the SOFT_TAB and LIT_ECHO modes in the LINEMODE support.
461 Add the "-l user" option to command line and open command
462 (This is passed through the ENVIRON option).
464 Add the "-e" command line option, for setting the escape
465 character.
467 Add the "-D", diagnostic, option to the server. This allows
468 the server to print out debug information, which is very
469 useful when trying to debug a telnet that doesn't have any
470 debugging ability.
472 Turn off the literal next character when not in LINEMODE.
474 Don't recognize ^Y locally, just pass it through.
476 Make minor modifications for Sun4.0 and Sun4.1
478 Add support for both FORW1 and FORW2 characters. The
479 telnet escpape character is set to whichever of the
480 two is not being used. If both are in use, the escape
481 character is not set, so when in linemode the user will
482 have to follow the escape character with a <CR> or <EOF)
483 to get it passed through.
485 Commands can now be put in single and double quotes, and
486 a backslash is now an escape character. This is needed
487 for allowing arbitrary strings to be assigned to environment
488 variables.
490 Switch telnetd to use macros like telnet for keeping
491 track of the state of all the options.
493 Fix telnetd's processing of options so that we always do
494 the right processing of the LINEMODE option, regardless
495 of who initiates the request to turn it on. Also, make
496 sure that if the other side went "WILL ECHO" in response
497 to our "DO ECHO", that we send a "DONT ECHO" to get the
498 option turned back off!
500 Fix the TERMIOS setting of the terminal speed to handle both
501 BSD's separate fields, and the SYSV method of CBAUD bits.
503 Change how we deal with the other side refusing to enable
504 an option. The sequence used to be: send DO option; receive
505 WONT option; send DONT option. Now, the sequence is: send
506 DO option; receive WONT option. Both should be valid
507 according to the spec, but there has been at least one
508 client implementation of telnet identified that can get
509 really confused by this. (The exact sequence, from a trace
510 on the server side, is (numbers are number of responses that
511 we expect to get after that line...):
513 send WILL ECHO 1 (initial request)
514 send WONT ECHO 2 (server is changing state)
515 recv DO ECHO 1 (first reply, ok. expect DONT ECHO next)
516 send WILL ECHO 2 (server changes state again)
517 recv DONT ECHO 1 (second reply, ok. expect DO ECHO next)
518 recv DONT ECHO 0 (third reply, wrong answer. got DONT!!!)
519 *** send WONT ECHO (send WONT to acknowledge the DONT)
520 send WILL ECHO 1 (ask again to enable option)
521 recv DO ECHO 0
523 recv DONT ECHO 0
524 send WONT ECHO 1
525 recv DONT ECHO 0
526 recv DO ECHO 1
527 send WILL ECHO 0
528 (and the last 5 lines loop forever)
530 The line with the "***" is last of the WILL/DONT/WONT sequence.
531 The change to the server to not generate that makes this same
532 example become:
534 send will ECHO 1
535 send wont ECHO 2
536 recv do ECHO 1
537 send will ECHO 2
538 recv dont ECHO 1
539 recv dont ECHO 0
540 recv do ECHO 1
541 send will ECHO 0
543 There is other option negotiation going on, and not sending
544 the third part changes some of the timings, but this specific
545 example no longer gets stuck in a loop. The "telnet.state"
546 file has been modified to reflect this change to the algorithm.
548 A bunch of miscellaneous bug fixes and changes to make
549 lint happier.
551 This version of telnet also has some KERBEROS stuff in
552 it. This has not been tested, it uses an un-authorized
553 telnet option number, and uses an out-of-date version
554 of the (still being defined) AUTHENTICATION option.
555 There is no support for this code, do not enable it.
558 March 1, 1990:
559 CHANGES/BUGFIXES SINCE LAST RELEASE:
560 Some support for IP TOS has been added. Requires that the
561 kernel support the IP_TOS socket option (currently this
562 is only in UNICOS 6.0).
564 Both telnet and telnetd now use the cc_t typedef. typedefs are
565 included for systems that don't have it (in termios.h).
567 SLC_SUSP was not supported properly before. It is now.
569 IAC EOF was not translated properly in telnetd for SYSV_TERMIO
570 when not in linemode. It now saves a copy of the VEOF character,
571 so that when ICANON is turned off and we can't trust it anymore
572 (because it is now the VMIN character) we use the saved value.
574 There were two missing "break" commands in the linemode
575 processing code in telnetd.
577 Telnetd wasn't setting the kernel window size information
578 properly. It was using the rows for both rows and columns...
580 Questions/comments go to
581 David Borman
582 Cray Research, Inc.
583 655F Lone Oak Drive
584 Eagan, MN 55123
585 dab@cray.com.
587 README: You are reading it.
589 Config.generic:
590 This file contains all the OS specific definitions. It
591 has pre-definitions for many common system types, and is
592 in standard makefile fromat. See the comments at the top
593 of the file for more information.
595 Config.local:
596 This is not part of the distribution, but if this file exists,
597 it is used instead of "Config.generic". This allows site
598 specific configuration without having to modify the distributed
599 "Config.generic" file.
601 kern.diff:
602 This file contains the diffs for the changes needed for the
603 kernel to support LINEMODE is the server. These changes are
604 for a 4.3BSD system. You may need to make some changes for
605 your particular system.
607 There is a new bit in the terminal state word, TS_EXTPROC.
608 When this bit is set, several aspects of the terminal driver
609 are disabled. Input line editing, character echo, and
610 mapping of signals are all disabled. This allows the telnetd
611 to turn of these functions when in linemode, but still keep
612 track of what state the user wants the terminal to be in.
614 New ioctl()s:
616 TIOCEXT Turn on/off the TS_EXTPROC bit
617 TIOCGSTATE Get t_state of tty to look at TS_EXTPROC bit
618 TIOCSIG Generate a signal to processes in the
619 current process group of the pty.
621 There is a new mode for packet driver, the TIOCPKT_IOCTL bit.
622 When packet mode is turned on in the pty, and the TS_EXTPROC
623 bit is set, then whenever the state of the pty is changed, the
624 next read on the master side of the pty will have the TIOCPKT_IOCTL
625 bit set, and the data will contain the following:
626 struct xx {
627 struct sgttyb a;
628 struct tchars b;
629 struct ltchars c;
630 int t_state;
631 int t_flags;
632 }
633 This allows the process on the server side of the pty to know
634 when the state of the terminal has changed, and what the new
635 state is.
637 However, if you define USE_TERMIO or SYSV_TERMIO, the code will
638 expect that the structure returned in the TIOCPKT_IOCTL is
639 the termio/termios structure.
641 stty.diff:
642 This file contains the changes needed for the stty(1) program
643 to report on the current status of the TS_EXTPROC bit. It also
644 allows the user to turn on/off the TS_EXTPROC bit. This is useful
645 because it allows the user to say "stty -extproc", and the
646 LINEMODE option will be automatically disabled, and saying "stty
647 extproc" will re-enable the LINEMODE option.
649 telnet.state:
650 Both the client and server have code in them to deal
651 with option negotiation loops. The algorithm that is
652 used is described in this file.
654 telnet:
655 This directory contains the client code. No kernel changes are
656 needed to use this code.
658 telnetd:
659 This directory contains the server code. If LINEMODE or KLUDGELINEMODE
660 are defined, then the kernel modifications listed above are needed.
662 libtelnet:
663 This directory contains code that is common to both the client
664 and the server.
666 arpa:
667 This directory has a new <arpa/telnet.h>
669 libtelnet/Makefile.4.4:
670 telnet/Makefile.4.4:
671 telnetd/Makefile.4.4:
672 These are the makefiles that can be used on a 4.3Reno
673 system when this software is installed in /usr/src/lib/libtelnet,
674 /usr/src/libexec/telnetd, and /usr/src/usr.bin/telnet.
677 The following TELNET options are supported:
679 LINEMODE:
680 The LINEMODE option is supported as per RFC1116. The
681 FORWARDMASK option is not currently supported.
683 BINARY: The client has the ability to turn on/off the BINARY
684 option in each direction. Turning on BINARY from
685 server to client causes the LITOUT bit to get set in
686 the terminal driver on both ends, turning on BINARY
687 from the client to the server causes the PASS8 bit
688 to get set in the terminal driver on both ends.
690 TERMINAL-TYPE:
691 This is supported as per RFC1091. On the server side,
692 when a terminal type is received, termcap/terminfo
693 is consulted to determine if it is a known terminal
694 type. It keeps requesting terminal types until it
695 gets one that it recongnizes, or hits the end of the
696 list. The server side looks up the entry in the
697 termcap/terminfo data base, and generates a list of
698 names which it then passes one at a time to each
699 request for a terminal type, duplicating the last
700 entry in the list before cycling back to the beginning.
702 NAWS: The Negotiate about Window Size, as per RFC 1073.
704 TERMINAL-SPEED:
705 Implemented as per RFC 1079
707 TOGGLE-FLOW-CONTROL:
708 Implemented as per RFC 1080
710 TIMING-MARK:
711 As per RFC 860
713 SGA: As per RFC 858
715 ECHO: As per RFC 857
717 LOGOUT: As per RFC 727
719 STATUS:
720 The server will send its current status upon
721 request. It does not ask for the clients status.
722 The client will request the servers current status
723 from the "send getstatus" command.
725 ENVIRON:
726 This option is currently being defined by the IETF
727 Telnet Working Group, and an RFC has not yet been
728 issued, but should be in the near future...
730 X-DISPLAY-LOCATION:
731 This functionality can be done through the ENVIRON
732 option, it is added here for completeness.
734 AUTHENTICATION:
735 This option is currently being defined by the IETF
736 Telnet Working Group, and an RFC has not yet been
737 issued. The basic framework is pretty much decided,
738 but the definitions for the specific authentication
739 schemes is still in a state of flux.
741 ENCRYPTION:
742 This option is currently being defined by the IETF
743 Telnet Working Group, and an RFC has not yet been
744 issued. The draft RFC is still in a state of flux,
745 so this code may change in the future.