telnet.tproj/README

   1
   2 This is a distribution of both client and server telnet.  These programs
   3 have been compiled on:
   4                         telnet  telnetd
   5         4.4 BSD-Lite      x       x
   6         4.3 BSD Reno      X       X
   7         UNICOS 9.1        X       X
   8         UNICOS 9.0        X       X
   9         UNICOS 8.0        X       X
  10         BSDI 2.0          X       X
  11         Solaris 2.4       x       x (no linemode in server)
  12         SunOs 4.1.4       X       X (no linemode in server)
  13         Ultrix 4.3        X       X (no linemode in server)
  14         Ultrix 4.1        X       X (no linemode in server)
  15
  16 In addition, previous versions have been compiled on the following
  17 machines, but were not available for testing this version.
  18                         telnet  telnetd
  19         Next1.0           X       X
  20         UNICOS 8.3        X       X
  21         UNICOS 7.C        X       X
  22         UNICOS 7.0        X       X
  23         SunOs 4.0.3c      X       X (no linemode in server)
  24         4.3 BSD           X       X (no linemode in server)
  25         DYNIX V3.0.12     X       X (no linemode in server)
  26         Ultrix 3.1        X       X (no linemode in server)
  27         Ultrix 4.0        X       X (no linemode in server)
  28         SunOs 3.5         X       X (no linemode in server)
  29         SunOs 4.1.3       X       X (no linemode in server)
  30         Solaris 2.2       x       x (no linemode in server)
  31         Solaris 2.3       x       x (no linemode in server)
  32         BSDI 1.0          X       X
  33         BSDI 1.1          X       X
  34         DYNIX V3.0.17.9   X       X (no linemode in server)
  35         HP-UX 8.0         x       x (no linemode in server)
  36
  37 This code should work, but there are no guarantees.
  38
  39 May 30, 1995
  40
  41 This release represents what is on the 4.4BSD-Lite2 release, which
  42 should be the final BSD release.  I will continue to support of
  43 telnet, The code (without encryption) is available via anonymous ftp
  44 from ftp.cray.com, in src/telnet/telnet.YY.MM.DD.NE.tar.Z, where
  45 YY.MM.DD is replaced with the year, month and day of the release.
  46 If you can't find it at one of these places, at some point in the
  47 near future information about the latest releases should be available
  48 from ftp.borman.com.
  49
  50 In addition, the version with the encryption code is available via
  51 ftp from net-dist.mit.edu, in the directory /pub/telnet.  There
  52 is a README file there that gives further information on how
  53 to get the distribution.
  54
  55 Questions, comments, bug reports and bug fixes can be sent to
  56 one of these addresses:
  57                 dab@borman.com
  58                 dab@cray.com
  59                 dab@bsdi.com
  60
  61 This release is mainly bug fixes and code cleanup.
  62
  63         Replace all calls to bcopy()/bzero() with calls to
  64         memmove()/memset() and all calls to index()/rindex()
  65         with calls to strchr()/strrchr().
  66
  67         Add some missing diagnostics for option tracing
  68         to telnetd.
  69
  70         Add support for BSDI 2.0 and Solaris 2.4.
  71
  72         Add support for UNICOS 8.0
  73
  74         Get rid of expanded tabs and trailing white spaces.
  75
  76         From Paul Vixie:
  77                 Fix for telnet going into an endless spin
  78                 when the session dies abnormally.
  79
  80         From Jef Poskanzer:
  81                 Changes to allow telnet to compile
  82                 under SunOS 3.5.
  83
  84         From Philip Guenther:
  85                 makeutx() doesn't expand utmpx,
  86                 use pututxline() instead.
  87
  88         From Chris Torek:
  89                 Add a sleep(1) before execing login
  90                 to avoid race condition that can eat
  91                 up the login prompt.
  92                 Use terminal speed directly if it is
  93                 not an encoded value.
  94
  95         From Steve Parker:
  96                 Fix to realloc() call.  Fix for execing
  97                 login on solaris with no user name.
  98
  99 January 19, 1994
 100
 101 This is a list of some of the changes since the last tar release
 102 of telnet/telnetd.  There are probably other changes that aren't
 103 listed here, but this should hit a lot of the main ones.
 104
 105    General:
 106         Changed #define for AUTHENTICATE to AUTHENTICATION
 107         Changed #define for ENCRYPT to ENCRYPTION
 108         Changed #define for DES_ENCRYPT to DES_ENCRYPTION
 109
 110         Added support for SPX authentication: -DSPX
 111
 112         Added support for Kerberos Version 5 authentication: -DKRB5
 113
 114         Added support for ANSI C function prototypes
 115
 116         Added support for the NEW-ENVIRON option (RFC-1572)
 117         including support for USERVAR.
 118
 119         Made support for the old Environment Option (RFC-1408)
 120         conditional on -DOLD_ENVIRON
 121
 122         Added #define ENV_HACK - support for RFC 1571
 123
 124         The encryption code is removed from the public distributions.
 125         Domestic 4.4 BSD distributions contain the encryption code.
 126
 127         ENV_HACK: Code to deal with systems that only implement
 128                 the old ENVIRON option, and have reversed definitions
 129                 of ENV_VAR and ENV_VAL.  Also fixes ENV processing in
 130                 client to handle things besides just the default set...
 131
 132         NO_BSD_SETJMP: UNICOS configuration for
 133                 UNICOS 6.1/6.0/5.1/5.0 systems.
 134
 135         STREAMSPTY: Use /dev/ptmx to get a clean pty.  This
 136                 is for SVr4 derivatives (Like Solaris)
 137
 138         UTMPX: For systems that have /etc/utmpx. This is for
 139                 SVr4 derivatives (Like Solaris)
 140
 141         Definitions for BSDI 1.0
 142
 143         Definitions for 4.3 Reno and 4.4 BSD.
 144
 145         Definitions for UNICOS 8.0 and UNICOS 7.C
 146
 147         Definitions for Solaris 2.0
 148
 149         Definitions for HP-UX 8.0
 150
 151         Latest Copyright notices from Berkeley.
 152
 153         FLOW-CONTROL: support for RFC-XXXx
 154
 155
 156    Client Specific:
 157
 158         Fix the "send" command to not send garbage...
 159
 160         Fix status message for "skiprc"
 161
 162         Make sure to send NAWS after telnet has been suspended
 163         or an external command has been run, if the window size
 164         has changed.
 165
 166         sysV88 support.
 167
 168    Server Specific:
 169
 170         Support flowcontrol option in non-linemode servers.
 171
 172         -k Server supports Kludge Linemode, but will default to
 173            either single character mode or real Linemode support.
 174            The user will have to explicitly ask to switch into
 175            kludge linemode. ("stty extproc", or escape back to
 176            to telnet and say "mode line".)
 177
 178         -u Specify the length of the hostname field in the utmp
 179            file.  Hostname longer than this length will be put
 180            into the utmp file in dotted decimal notation, rather
 181            than putting in a truncated hostname.
 182
 183         -U Registered hosts only.  If a reverse hostname lookup
 184            fails, the connection will be refused.
 185
 186         -f/-F
 187            Allows forwarding of credentials for KRB5.
 188
 189 Februrary 22, 1991:
 190
 191     Features:
 192
 193         This version of telnet/telnetd has support for both
 194         the AUTHENTICATION and ENCRYPTION options.  The
 195         AUTHENTICATION option is fairly well defined, and
 196         an option number has been assigned to it.  The
 197         ENCRYPTION option is still in a state of flux; an
 198         option number has been assigned to, but it is still
 199         subject to change.  The code is provided in this release
 200         for experimental and testing purposes.
 201
 202         The telnet "send" command can now be used to send
 203         do/dont/will/wont commands, with any telnet option
 204         name.  The rules for when do/dont/will/wont are sent
 205         are still followed, so just because the user requests
 206         that one of these be sent doesn't mean that it will
 207         be sent...
 208
 209         The telnet "getstatus" command no longer requires
 210         that option printing be enabled to see the response
 211         to the "DO STATUS" command.
 212
 213         A -n flag has been added to telnetd to disable
 214         keepalives.
 215
 216         A new telnet command, "auth" has been added (if
 217         AUTHENTICATE is defined).  It has four sub-commands,
 218         "status", "disable", "enable" and "help".
 219
 220         A new telnet command, "encrypt" has been added (if
 221         ENCRYPT is defined).  It has many sub-commands:
 222         "enable", "type", "start", "stop", "input",
 223         "-input", "output", "-output", "status", and "help".
 224
 225         The LOGOUT option is now supported by both telnet
 226         and telnetd, a new command, "logout", was added
 227         to support this.
 228
 229         Several new toggle options were added:
 230             "autoencrypt", "autodecrypt", "autologin", "authdebug",
 231             "encdebug", "skiprc", "verbose_encrypt"
 232
 233         An "rlogin" interface has been added.  If the program
 234         is named "rlogin", or the "-r" flag is given, then
 235         an rlogin type of interface will be used.
 236                 ~.      Terminates the session
 237                 ~<susp> Suspend the session
 238                 ~^]     Escape to telnet command mode
 239                 ~~      Pass through the ~.
 240             BUG: If you type the rlogin escape character
 241                  in the middle of a line while in rlogin
 242                  mode, you cannot erase it or any characters
 243                  before it.  Hopefully this can be fixed
 244                  in a future release...
 245
 246     General changes:
 247
 248         A "libtelnet.a" has now been created.  This libraray
 249         contains code that is common to both telnet and
 250         telnetd.  This is also where library routines that
 251         are needed, but are not in the standard C library,
 252         are placed.
 253
 254         The makefiles have been re-done.  All of the site
 255         specific configuration information has now been put
 256         into a single "Config.generic" file, in the top level
 257         directory.  Changing this one file will take care of
 258         all three subdirectories.  Also, to add a new/local
 259         definition, a "Config.local" file may be created
 260         at the top level; if that file exists, the subdirectories
 261         will use that file instead of "Config.generic".
 262
 263         Many 1-2 line functions in commands.c have been
 264         removed, and just inserted in-line, or replaced
 265         with a macro.
 266
 267     Bug Fixes:
 268
 269         The non-termio code in both telnet and telnetd was
 270         setting/clearing CTLECH in the sg_flags word.  This
 271         was incorrect, and has been changed to set/clear the
 272         LCTLECH bit in the local mode word.
 273
 274         The SRCRT #define has been removed.  If IP_OPTIONS
 275         and IPPROTO_IP are defined on the system, then the
 276         source route code is automatically enabled.
 277
 278         The NO_GETTYTAB #define has been removed; there
 279         is a compatability routine that can be built into
 280         libtelnet to achive the same results.
 281
 282         The server, telnetd, has been switched to use getopt()
 283         for parsing the argument list.
 284
 285         The code for getting the input/output speeds via
 286         cfgetispeed()/cfgetospeed() was still not quite
 287         right in telnet.  Posix says if the ispeed is 0,
 288         then it is really equal to the ospeed.
 289
 290         The suboption processing code in telnet now has
 291         explicit checks to make sure that we received
 292         the entire suboption (telnetd was already doing this).
 293
 294         The telnet code for processing the terminal type
 295         could cause a core dump if an existing connection
 296         was closed, and a new connection opened without
 297         exiting telnet.
 298
 299         Telnetd was doing a TCSADRAIN when setting the new
 300         terminal settings;  This is not good, because it means
 301         that the tcsetattr() will hang waiting for output to
 302         drain, and telnetd is the only one that will drain
 303         the output...  The fix is to use TCSANOW which does
 304         not wait.
 305
 306         Telnetd was improperly setting/clearing the ISTRIP
 307         flag in the c_lflag field, it should be using the
 308         c_iflag field.
 309
 310         When the child process of telnetd was opening the
 311         slave side of the pty, it was re-setting the EXTPROC
 312         bit too early, and some of the other initialization
 313         code was wiping it out.  This would cause telnetd
 314         to go out of linemode and into single character mode.
 315
 316         One instance of leaving linemode in telnetd forgot
 317         to send a WILL ECHO to the client, the net result
 318         would be that the user would see double character
 319         echo.
 320
 321         If the MODE was being changed several times very
 322         quickly, telnetd could get out of sync with the
 323         state changes and the returning acks; and wind up
 324         being left in the wrong state.
 325
 326 September 14, 1990:
 327
 328         Switch the client to use getopt() for parsing the
 329         argument list.  The 4.3Reno getopt.c is included for
 330         systems that don't have getopt().
 331
 332         Use the posix _POSIX_VDISABLE value for what value
 333         to use when disabling special characters.  If this
 334         is undefined, it defaults to 0x3ff.
 335
 336         For non-termio systems, TIOCSETP was being used to
 337         change the state of the terminal.  This causes the
 338         input queue to be flushed, which we don't want.  This
 339         is now changed to TIOCSETN.
 340
 341         Take out the "#ifdef notdef" around the code in the
 342         server that generates a "sync" when the pty oputput
 343         is flushed.  The potential problem is that some older
 344         telnet clients may go into an infinate loop when they
 345         receive a "sync", if so, the server can be compiled
 346         with "NO_URGENT" defined.
 347
 348         Fix the client where it was setting/clearing the OPOST
 349         bit in the c_lflag field, not the c_oflag field.
 350
 351         Fix the client where it was setting/clearing the ISTRIP
 352         bit in the c_lflag field, not the c_iflag field.  (On
 353         4.3Reno, this is the ECHOPRT bit in the c_lflag field.)
 354         The client also had its interpretation of WILL BINARY
 355         and DO BINARY reversed.
 356
 357         Fix a bug in client that would cause a core dump when
 358         attempting to remove the last environment variable.
 359
 360         In the client, there were a few places were switch()
 361         was being passed a character, and if it was a negative
 362         value, it could get sign extended, and not match
 363         the 8 bit case statements.  The fix is to and the
 364         switch value with 0xff.
 365
 366         Add a couple more printoption() calls in the client, I
 367         don't think there are any more places were a telnet
 368         command can be received and not printed out when
 369         "options" is on.
 370
 371         A new flag has been added to the client, "-a".  Currently,
 372         this just causes the USER name to be sent across, in
 373         the future this may be used to signify that automatic
 374         authentication is requested.
 375
 376         The USER variable is now only sent by the client if
 377         the "-a" or "-l user" options are explicity used, or
 378         if the user explicitly asks for the "USER" environment
 379         variable to be exported.  In the server, if it receives
 380         the "USER" environment variable, it won't print out the
 381         banner message, so that only "Password:" will be printed.
 382         This makes the symantics more like rlogin, and should be
 383         more familiar to the user.  (People are not used to
 384         getting a banner message, and then getting just a
 385         "Password:" prompt.)
 386
 387         Re-vamp the code for starting up the child login
 388         process.  The code was getting ugly, and it was
 389         hard to tell what was really going on.  What we
 390         do now is after the fork(), in the child:
 391                 1) make sure we have no controlling tty
 392                 2) open and initialize the tty
 393                 3) do a setsid()/setpgrp()
 394                 4) makes the tty our controlling tty.
 395         On some systems, #2 makes the tty our controlling
 396         tty, and #4 is a no-op.  The parent process does
 397         a gets rid of any controlling tty after the child
 398         is fork()ed.
 399
 400         Use the strdup() library routine in telnet, instead
 401         of the local savestr() routine.  If you don't have
 402         strdup(), you need to define NO_STRDUP.
 403
 404         Add support for ^T (SIGINFO/VSTATUS), found in the
 405         4.3Reno distribution.  This maps to the AYT character.
 406         You need a 4-line bugfix in the kernel to get this
 407         to work properly:
 408
 409         > *** tty_pty.c.ORG     Tue Sep 11 09:41:53 1990
 410         > --- tty_pty.c Tue Sep 11 17:48:03 1990
 411         > ***************
 412         > *** 609,613 ****
 413         >                       if ((tp->t_lflag&NOFLSH) == 0)
 414         >                               ttyflush(tp, FREAD|FWRITE);
 415         > !                     pgsignal(tp->t_pgrp, *(unsigned int *)data);
 416         >                       return(0);
 417         >               }
 418         > --- 609,616 ----
 419         >                       if ((tp->t_lflag&NOFLSH) == 0)
 420         >                               ttyflush(tp, FREAD|FWRITE);
 421         > !                     pgsignal(tp->t_pgrp, *(unsigned int *)data, 1);
 422         > !                     if ((*(unsigned int *)data == SIGINFO) &&
 423         > !                         ((tp->t_lflag&NOKERNINFO) == 0))
 424         > !                             ttyinfo(tp);
 425         >                       return(0);
 426         >               }
 427
 428         The client is now smarter when setting the telnet escape
 429         character; it only sets it to one of VEOL and VEOL2 if
 430         one of them is undefined, and the other one is not already
 431         defined to the telnet escape character.
 432
 433         Handle TERMIOS systems that have seperate input and output
 434         line speed settings imbedded in the flags.
 435
 436         Many other minor bug fixes.
 437
 438 June 20, 1990:
 439         Re-organize makefiles and source tree.  The telnet/Source
 440         directory is now gone, and all the source that was in
 441         telnet/Source is now just in the telnet directory.
 442
 443         Seperate makefile for each system are now gone.  There
 444         are two makefiles, Makefile and Makefile.generic.
 445         The "Makefile" has the definitions for the various
 446         system, and "Makefile.generic" does all the work.
 447         There is a variable called "WHAT" that is used to
 448         specify what to make.  For example, in the telnet
 449         directory, you might say:
 450                 make 4.4bsd WHAT=clean
 451         to clean out the directory.
 452
 453         Add support for the ENVIRON and XDISPLOC options.
 454         In order for the server to work, login has to have
 455         the "-p" option to preserve environment variables.
 456
 457         Add the SOFT_TAB and LIT_ECHO modes in the LINEMODE support.
 458
 459         Add the "-l user" option to command line and open command
 460         (This is passed through the ENVIRON option).
 461
 462         Add the "-e" command line option, for setting the escape
 463         character.
 464
 465         Add the "-D", diagnostic, option to the server.  This allows
 466         the server to print out debug information, which is very
 467         useful when trying to debug a telnet that doesn't have any
 468         debugging ability.
 469
 470         Turn off the literal next character when not in LINEMODE.
 471
 472         Don't recognize ^Y locally, just pass it through.
 473
 474         Make minor modifications for Sun4.0 and Sun4.1
 475
 476         Add support for both FORW1 and FORW2 characters.  The
 477         telnet escpape character is set to whichever of the
 478         two is not being used.  If both are in use, the escape
 479         character is not set, so when in linemode the user will
 480         have to follow the escape character with a <CR> or <EOF)
 481         to get it passed through.
 482
 483         Commands can now be put in single and double quotes, and
 484         a backslash is now an escape character.  This is needed
 485         for allowing arbitrary strings to be assigned to environment
 486         variables.
 487
 488         Switch telnetd to use macros like telnet for keeping
 489         track of the state of all the options.
 490
 491         Fix telnetd's processing of options so that we always do
 492         the right processing of the LINEMODE option, regardless
 493         of who initiates the request to turn it on.  Also, make
 494         sure that if the other side went "WILL ECHO" in response
 495         to our "DO ECHO", that we send a "DONT ECHO" to get the
 496         option turned back off!
 497
 498         Fix the TERMIOS setting of the terminal speed to handle both
 499         BSD's seperate fields, and the SYSV method of CBAUD bits.
 500
 501         Change how we deal with the other side refusing to enable
 502         an option.  The sequence used to be: send DO option; receive
 503         WONT option; send DONT option.  Now, the sequence is: send
 504         DO option; receive WONT option.  Both should be valid
 505         according to the spec, but there has been at least one
 506         client implementation of telnet identified that can get
 507         really confused by this.  (The exact sequence, from a trace
 508         on the server side, is (numbers are number of responses that
 509         we expect to get after that line...):
 510
 511                 send WILL ECHO  1 (initial request)
 512                 send WONT ECHO  2 (server is changing state)
 513                 recv DO ECHO    1 (first reply, ok.  expect DONT ECHO next)
 514                 send WILL ECHO  2 (server changes state again)
 515                 recv DONT ECHO  1 (second reply, ok.  expect DO ECHO next)
 516                 recv DONT ECHO  0 (third reply, wrong answer. got DONT!!!)
 517         ***     send WONT ECHO    (send WONT to acknowledge the DONT)
 518                 send WILL ECHO  1 (ask again to enable option)
 519                 recv DO ECHO    0
 520
 521                 recv DONT ECHO  0
 522                 send WONT ECHO  1
 523                 recv DONT ECHO  0
 524                 recv DO ECHO    1
 525                 send WILL ECHO  0
 526                 (and the last 5 lines loop forever)
 527
 528         The line with the "***" is last of the WILL/DONT/WONT sequence.
 529         The change to the server to not generate that makes this same
 530         example become:
 531
 532                 send will ECHO  1
 533                 send wont ECHO  2
 534                 recv do ECHO    1
 535                 send will ECHO  2
 536                 recv dont ECHO  1
 537                 recv dont ECHO  0
 538                 recv do ECHO    1
 539                 send will ECHO  0
 540
 541         There is other option negotiation going on, and not sending
 542         the third part changes some of the timings, but this specific
 543         example no longer gets stuck in a loop.  The "telnet.state"
 544         file has been modified to reflect this change to the algorithm.
 545
 546         A bunch of miscellaneous bug fixes and changes to make
 547         lint happier.
 548
 549         This version of telnet also has some KERBEROS stuff in
 550         it. This has not been tested, it uses an un-authorized
 551         telnet option number, and uses an out-of-date version
 552         of the (still being defined) AUTHENTICATION option.
 553         There is no support for this code, do not enable it.
 554
 555
 556 March 1, 1990:
 557 CHANGES/BUGFIXES SINCE LAST RELEASE:
 558         Some support for IP TOS has been added.  Requires that the
 559         kernel support the IP_TOS socket option (currently this
 560         is only in UNICOS 6.0).
 561
 562         Both telnet and telnetd now use the cc_t typedef.  typedefs are
 563         included for systems that don't have it (in termios.h).
 564
 565         SLC_SUSP was not supported properly before.  It is now.
 566
 567         IAC EOF was not translated  properly in telnetd for SYSV_TERMIO
 568         when not in linemode.  It now saves a copy of the VEOF character,
 569         so that when ICANON is turned off and we can't trust it anymore
 570         (because it is now the VMIN character) we use the saved value.
 571
 572         There were two missing "break" commands in the linemode
 573         processing code in telnetd.
 574
 575         Telnetd wasn't setting the kernel window size information
 576         properly.  It was using the rows for both rows and columns...
 577
 578 Questions/comments go to
 579                 David Borman
 580                 Cray Research, Inc.
 581                 655F Lone Oak Drive
 582                 Eagan, MN 55123
 583                 dab@cray.com.
 584
 585 README: You are reading it.
 586
 587 Config.generic:
 588         This file contains all the OS specific definitions.  It
 589         has pre-definitions for many common system types, and is
 590         in standard makefile fromat.  See the comments at the top
 591         of the file for more information.
 592
 593 Config.local:
 594         This is not part of the distribution, but if this file exists,
 595         it is used instead of "Config.generic".  This allows site
 596         specific configuration without having to modify the distributed
 597         "Config.generic" file.
 598
 599 kern.diff:
 600         This file contains the diffs for the changes needed for the
 601         kernel to support LINEMODE is the server.  These changes are
 602         for a 4.3BSD system.  You may need to make some changes for
 603         your particular system.
 604
 605         There is a new bit in the terminal state word, TS_EXTPROC.
 606         When this bit is set, several aspects of the terminal driver
 607         are disabled.  Input line editing, character echo, and
 608         mapping of signals are all disabled.  This allows the telnetd
 609         to turn of these functions when in linemode, but still keep
 610         track of what state the user wants the terminal to be in.
 611
 612         New ioctl()s:
 613
 614                 TIOCEXT         Turn on/off the TS_EXTPROC bit
 615                 TIOCGSTATE      Get t_state of tty to look at TS_EXTPROC bit
 616                 TIOCSIG         Generate a signal to processes in the
 617                                 current process group of the pty.
 618
 619         There is a new mode for packet driver, the TIOCPKT_IOCTL bit.
 620         When packet mode is turned on in the pty, and the TS_EXTPROC
 621         bit is set, then whenever the state of the pty is changed, the
 622         next read on the master side of the pty will have the TIOCPKT_IOCTL
 623         bit set, and the data will contain the following:
 624                 struct xx {
 625                         struct sgttyb a;
 626                         struct tchars b;
 627                         struct ltchars c;
 628                         int t_state;
 629                         int t_flags;
 630                 }
 631         This allows the process on the server side of the pty to know
 632         when the state of the terminal has changed, and what the new
 633         state is.
 634
 635         However, if you define USE_TERMIO or SYSV_TERMIO, the code will
 636         expect that the structure returned in the TIOCPKT_IOCTL is
 637         the termio/termios structure.
 638
 639 stty.diff:
 640         This file contains the changes needed for the stty(1) program
 641         to report on the current status of the TS_EXTPROC bit.  It also
 642         allows the user to turn on/off the TS_EXTPROC bit.  This is useful
 643         because it allows the user to say "stty -extproc", and the
 644         LINEMODE option will be automatically disabled, and saying "stty
 645         extproc" will re-enable the LINEMODE option.
 646
 647 telnet.state:
 648         Both the client and server have code in them to deal
 649         with option negotiation loops.  The algorithm that is
 650         used is described in this file.
 651
 652 telnet:
 653         This directory contains the client code.  No kernel changes are
 654         needed to use this code.
 655
 656 telnetd:
 657         This directory contains the server code.  If LINEMODE or KLUDGELINEMODE
 658         are defined, then the kernel modifications listed above are needed.
 659
 660 libtelnet:
 661         This directory contains code that is common to both the client
 662         and the server.
 663
 664 arpa:
 665         This directory has a new <arpa/telnet.h>
 666
 667 libtelnet/Makefile.4.4:
 668 telnet/Makefile.4.4:
 669 telnetd/Makefile.4.4:
 670         These are the makefiles that can be used on a 4.3Reno
 671         system when this software is installed in /usr/src/lib/libtelnet,
 672         /usr/src/libexec/telnetd, and /usr/src/usr.bin/telnet.
 673
 674
 675 The following TELNET options are supported:
 676
 677         LINEMODE:
 678                 The LINEMODE option is supported as per RFC1116.  The
 679                 FORWARDMASK option is not currently supported.
 680
 681         BINARY: The client has the ability to turn on/off the BINARY
 682                 option in each direction.  Turning on BINARY from
 683                 server to client causes the LITOUT bit to get set in
 684                 the terminal driver on both ends,  turning on BINARY
 685                 from the client to the server causes the PASS8 bit
 686                 to get set in the terminal driver on both ends.
 687
 688         TERMINAL-TYPE:
 689                 This is supported as per RFC1091.  On the server side,
 690                 when a terminal type is received, termcap/terminfo
 691                 is consulted to determine if it is a known terminal
 692                 type.  It keeps requesting terminal types until it
 693                 gets one that it recongnizes, or hits the end of the
 694                 list.  The server side looks up the entry in the
 695                 termcap/terminfo data base, and generates a list of
 696                 names which it then passes one at a time to each
 697                 request for a terminal type, duplicating the last
 698                 entry in the list before cycling back to the beginning.
 699
 700         NAWS:   The Negotiate about Window Size, as per RFC 1073.
 701
 702         TERMINAL-SPEED:
 703                 Implemented as per RFC 1079
 704
 705         TOGGLE-FLOW-CONTROL:
 706                 Implemented as per RFC 1080
 707
 708         TIMING-MARK:
 709                 As per RFC 860
 710
 711         SGA:    As per RFC 858
 712
 713         ECHO:   As per RFC 857
 714
 715         LOGOUT: As per RFC 727
 716
 717         STATUS:
 718                 The server will send its current status upon
 719                 request.  It does not ask for the clients status.
 720                 The client will request the servers current status
 721                 from the "send getstatus" command.
 722
 723         ENVIRON:
 724                 This option is currently being defined by the IETF
 725                 Telnet Working Group, and an RFC has not yet been
 726                 issued, but should be in the near future...
 727
 728         X-DISPLAY-LOCATION:
 729                 This functionality can be done through the ENVIRON
 730                 option, it is added here for completeness.
 731
 732         AUTHENTICATION:
 733                 This option is currently being defined by the IETF
 734                 Telnet Working Group, and an RFC has not yet been
 735                 issued.  The basic framework is pretty much decided,
 736                 but the definitions for the specific authentication
 737                 schemes is still in a state of flux.
 738
 739         ENCRYPTION:
 740                 This option is currently being defined by the IETF
 741                 Telnet Working Group, and an RFC has not yet been
 742                 issued.  The draft RFC is still in a state of flux,
 743                 so this code may change in the future.