
TELNET OPTIONS

(last updated 2003-11-06)

The Telnet Protocol has a number of options that may be negotiated.
These options are listed here.  "Internet Official Protocol Standards"
(STD 1) provides more detailed information.

Options  Name                                              References
-------  -----------------------                           ----------
   0     Binary Transmission                                 [RFC856]
   1     Echo                                                [RFC857]
   2     Reconnection                                      [NIC50005]
   3     Suppress Go Ahead                                   [RFC858]
   4     Approx Message Size Negotiation                   [ETHERNET]
   5     Status                                              [RFC859]
   6     Timing Mark                                         [RFC860]
   7     Remote Controlled Trans and Echo                    [RFC726]
   8     Output Line Width                                 [NIC50005]
   9     Output Page Size                                  [NIC50005]
  10     Output Carriage-Return Disposition                  [RFC652]
  11     Output Horizontal Tab Stops                         [RFC653]
  12     Output Horizontal Tab Disposition                   [RFC654]
  13     Output Formfeed Disposition                         [RFC655]
  14     Output Vertical Tabstops                            [RFC656]
  15     Output Vertical Tab Disposition                     [RFC657]
  16     Output Linefeed Disposition                         [RFC658]
  17     Extended ASCII                                      [RFC698]
  18     Logout                                              [RFC727]
  19     Byte Macro                                          [RFC735]
  20     Data Entry Terminal                         [RFC1043,RFC732]
  21     SUPDUP                                       [RFC736,RFC734]
  22     SUPDUP Output                                       [RFC749]
  23     Send Location                                       [RFC779]
  24     Terminal Type                                      [RFC1091]
  25     End of Record                                       [RFC885]
  26     TACACS User Identification                          [RFC927]
  27     Output Marking                                      [RFC933]
  28     Terminal Location Number                            [RFC946]
  29     Telnet 3270 Regime                                 [RFC1041]
  30     X.3 PAD                                            [RFC1053]
  31     Negotiate About Window Size                        [RFC1073]
  32     Terminal Speed                                     [RFC1079]
  33     Remote Flow Control                                [RFC1372]
  34     Linemode                                           [RFC1184]
  35     X Display Location                                 [RFC1096]
  36     Environment Option                                 [RFC1408]
  37     Authentication Option                              [RFC2941]
  38     Encryption Option                                  [RFC2946]
  39     New Environment Option                             [RFC1572]
  40     TN3270E                                            [RFC1647]
  41     XAUTH                                              [Earhart]
  42     CHARSET                                            [RFC2066]
  43	 Telnet Remote Serial Port (RSP)                     [Barnes]
  44     Com Port Control Option                            [RFC2217]
  45     Telnet Suppress Local Echo                           [Atmar]
  46     Telnet Start TLS                                       [Boe]
  47     KERMIT                                             [RFC2840]
  48     SEND-URL                                             [Croft]
  49	 FORWARD_X					     [Altman]
 50-137  Unassigned					       [IANA]
 138     TELOPT PRAGMA LOGON				  [McGregory]
 139	 TELOPT SSPI LOGON                                [McGregory]
 140     TELOPT PRAGMA HEARTBEAT                          [McGregory]
 255     Extended-Options-List                               [RFC861]

Telnet Authentication Types (Option 37)

In [RFC2941], a list of authentication commands and types is
documented.  Additions to the list are registerd by the IANA and
documented here.  Note: Authentication types followed by (*) were
never submitted to the IETF for consideration as an Internet standard.

Command    Description                  Reference
  0        IS                           [RFC2941]
  1        SEND                         [RFC2941]
  2        REPLY                        [RFC2941]
  3        NAME                         [RFC2941]

Type       Description                  Reference
  0        NULL                         [RFC2941]
  1        KERBEROS_V4                  [RFC2941]
  2        KERBEROS_V5                  [RFC2942]
  3        SPX                          [RFC2941] *
  4        MINK                         [RFC2941] *
  5        SRP                          [RFC2944]
  6        RSA (also used by SRA)       [RFC2941]
  7	   SSL                          [RFC2941]
  8-9	   Unassigned			   [IANA]
 10        LOKI                         [RFC2941] *
 11        SSA                           [Schoch]
 12	   KEA_SJ                       [RFC2951]
 13	   KEA_SJ_INTEG			[RFC2951]
 14 	   DSS				[RFC2943]
 15        NTLM                            [Kahn] *

In [RFC 1411], on the KERBEROS_V4 Telnet Authentication type there are
a set of Suboption Commands.  Additions to the list are registerd by
the IANA and documented here.

Suboption	Command                  Reference
   0            AUTH                     [RFC1411]
   1            REJECT                   [RFC1411]
   2            ACCEPT                   [RFC1411]
   3            CHALLENGE                [RFC1411]
   4            RESPONSE                 [RFC1411]
   5            FORWARD                 [Brashear]
   6            FORWARD-ACCEPT          [Brashear]
   7            FORWARD-REJECT          [Brashear]
   8            EXP                           [Wu]
   9            PARAMS                        [Wu]


In the KERBEROS_V5 Telnet Authentication type there are a set of
Suboption Commands.  Additions to the list are registerd by the IANA
and documented here.

Suboption       Command                  Reference
   0            AUTH                     [RFC2942]
   1            REJECT                   [RFC2942]
   2            ACCEPT                   [RFC2942]
   3            RESPONSE                 [RFC2942]
   4            FORWARD                  [RFC2942]
   5            FORWARD_ACCEPT           [RFC2942]
   6            FORWARD-REJECT           [RFC2942]


In the DSS Telnet Authentication type there are a set of
Suboption Commands.  Additions to the list are registerd by the IANA
and documented here.

Suboption       Command                  Reference
   1            DSS_INITIALIZE           [RFC2943]
   2            DSS_TOKENBA              [RFC2943]
   3            DSS_CERTA_TOKENAB        [RFC2943]
   4            DSS_CERTB_TOKENBA2       [RFC2943]


In the SRP Telnet Authentication type there are a set of Suboption
Commands.  Additions to the list are registerd by the IANA and
documented here.

Suboption       Command                  Reference
   0            AUTH                     [RFC2944]
   1            REJECT                   [RFC2944]
   2            ACCEPT                   [RFC2944]
   3            CHALLENGE                [RFC2944]
   4            RESPONSE                 [RFC2944]
   5-7          Unassigned               [RFC2944]
   8            EXP                      [RFC2944]
   9            PARAMS                   [RFC2944]


In the KEA_SJ and KEA_SJ_INTEG Telnet Authentication types, there are
a set of Suboption Commands.  Additions to the list are registerd by
the IANA and documented here.

Suboption       Command                  Reference
   1            KEA_CERTA_RA             [RFC2951]
   2            KEA_CERTB_RB_IVB_NONCEB  [RFC2951]
   3            KEA_IVA_RESPONSEB_NONCEA [RFC2951]
   4            KEA_RESPONSEA            [RFC2951]


Telnet Encryption Types (Option 38)

In the Telnet Encryption commands and types [RFC2946] there have been
various implementations in several widely distributed versions of
Telnet (e.g., at MIT, Stanford, and Columbia).  Originally, only two
encryption types were specified.  Additional encryption types have
been defined and are listed below.  Additions to the list are
registerd by the IANA and documented here.

Command

   0    IS                               [RFC2946]
   1    SUPPORT                          [RFC2946]
   2    REPLY                            [RFC2946]
   3    START                            [RFC2946]
   4    END                              [RFC2946]
   5    REQUEST-START                    [RFC2946]
   6    REQUEST-END                      [RFC2946]
   7    ENC_KEYID                        [RFC2946]
   8    DEC_KEYID                        [RFC2946]

Type                               

   0    NULL				  [RFC2946]
   1	DES_CFB64                         [RFC2946]
   2	DES_OFB64                         [RFC2946]
   3    DES3_CFB64                        [RFC2946]
   4    DES3_OFB64                        [RFC2946]
   5-7	Unassigned                           [IANA]
   8	CAST5_40_CFB64                    [RFC2946]
   9    CAST5_40_OFB64                    [RFC2946]
  10    CAST128_CFB64                     [RFC2946]
  11    CAST128_OFB64                     [RFC2946]
  12    AES_CCM                         [Josefsson]

In the DES3_CFB64 Telnet Encryption type there are a set of Suboption
Commands.  Additions to the list are registerd by the IANA and
documented here.

Suboption       Command                  Reference
   1            CFB64_IV                 [RFC2947]
   2            CFB64_IV_OK              [RFC2947]
   3            CFB64_IV_BAD             [RFC2947]


In the DES3_OFB64 Telnet Encryption type there are a set of Suboption
Commands.  Additions to the list are registerd by the IANA and
documented here.

Suboption       Command                  Reference
   1            OFB64_IV                 [RFC2948]
   2            OFB64_IV_OK              [RFC2948]
   3            OFB64_IV_BAD             [RFC2948]


In the CAST5_40_OFB64 and CAST128_OFB64 Telnet Encryption types, there
are a set of Suboption Commands.  Additions to the list are registerd
by the IANA and documented here.

Suboption       Command                  Reference
   1            OFB64_IV                 [RFC2949]
   2            OFB64_IV_OK              [RFC2949]
   3            OFB64_IV_BAD             [RFC2949]


In the CAST5_40_CFB64 and CAST128_CFB64 Telnet Encryption types, there
are a set of Suboption Commands.  Additions to the list are registerd
by the IANA and documented here.

Suboption       Command                  Reference
   1            CFB64_IV                 [RFC2950]
   2            CFB64_IV_OK              [RFC2950]
   3            CFB64_IV_BAD             [RFC2950]


In the DES_CFB64 Telnet Encryption type there are a set of Suboption
Commands.  Additions to the list are registerd by the IANA and
documented here.

Suboption       Command                  Reference
   1            CFB64_IV                 [RFC2952]
   2            CFB64_IV_OK              [RFC2952]
   3            CFB64_IV_BAD             [RFC2952]


In the DES_OFB64 Telnet Encryption type there are a set of Suboption
Commands.  Additions to the list are registerd by the IANA and
documented here.

Suboption       Command                  Reference
   1            OFB64_IV                 [RFC2953]
   2            OFB64_IV_OK              [RFC2953]
   3            OFB64_IV_BAD             [RFC2953]


REFERENCES

[ETHERNET] "The Ethernet, A Local Area Network: Data Link Layer and
           Physical Layer Specification", AA-K759B-TK, Digital
           Equipment Corporation, Maynard, MA.  Also as: "The
           Ethernet - A Local Area Network", Version 1.0, Digital
           Equipment Corporation, Intel Corporation, Xerox
           Corporation, September 1980.  And: "The Ethernet, A Local
           Area Network: Data Link Layer and Physical Layer
           Specifications", Digital, Intel and Xerox, November 1982.
           And: XEROX, "The Ethernet, A Local Area Network: Data Link
           Layer and Physical Layer Specification", X3T51/80-50, Xerox
           Corporation, Stamford, CT., October 1980.

[NIC50005] DDN Protocol Handbook, "Telnet Reconnection Option",
           "Telnet Output Line Width Option", "Telnet Output Page Size
           Option", NIC 50005, December 1985.

[RFC652] Crocker, D., "Telnet Output Carriage-Return Disposition
         Option", RFC 652, UCLA-NMC, October 1974.

[RFC653] Crocker, D., "Telnet Output Horizontal Tabstops Option",
         RFC 653, UCLA-NMC, October 1974.

[RFC654] Crocker, D., "Telnet Output Horizontal Tab Disposition
         Option", RFC 654, UCLA-NMC, October 1974.

[RFC655] Crocker, D., "Telnet Output Formfeed Disposition Option",
         RFC 655, UCLA-NMC, October 1974.

[RFC656] Crocker, D., "Telnet Output Vertical Tabstops Option",
         RFC 656, UCLA-NMC, October 1974.

[RFC657] Crocker, D., "Telnet Output Vertical Tab Disposition Option",
         RFC 657, UCLA-NMC, October 1974.

[RFC658] Crocker, D., "Telnet Output Linefeed Disposition", RFC 658,
         UCLA-NMC, October 1974.

[RFC698] Tovar, "Telnet Extended ASCII Option", RFC 698, Stanford
         University-AI, July 1975.

[RFC726] Postel, J. and D. Crocker, "Remote Controlled Transmission
         and Echoing Telnet Option", RFC 726, SRI-ARC, UC Irvine,
         March 1977.

[RFC727] Crispin, M., "Telnet Logout Option", RFC 727, Stanford
         University-AI, April 1977.

[RFC734] Crispin, M., "SUPDUP Protocol", RFC 734, Stanford,
         October 1977.

[RFC735] Crocker, D. and R. Gumpertz, "Revised Telnet Byte Marco
         Option", RFC 735, Rand, CMU, November 1977.

[RFC736] Crispin, M., "Telnet SUPDUP Option", Stanford University-AI,
         RFC 736, Stanford, October 1977.

[RFC749] Greenberg, B., "Telnet SUPDUP-OUTPUT Option", RFC 749,
         MIT-Multics, September 1978.

[RFC779] Killian, E., "Telnet Send-Location Option", RFC 779,
         LLL, April 1981.

[RFC856] Postel, J. and J. Reynolds, "Telnet Binary Transmission",
         STD 27, RFC 856, USC/Information Sciences Institute, May
         1983.

[RFC857] Postel, J. and J. Reynolds, "Telnet Echo Option", STD 28, RFC
         857, USC/Information Sciences Institute, May 1983.

[RFC858] Postel, J. and J. Reynolds, "Telnet Suppress Go Ahead
         Option", STD 29, RFC 858, USC/Information Sciences Institute,
         May 1983.

[RFC859] Postel, J. and J. Reynolds, "Telnet Status Option", STD 30,
         RFC 859, USC/Information Sciences Institute, May 1983.

[RFC860] Postel, J. and J. Reynolds, "Telnet Timing Mark Option",
         STD 31, RFC 860, USC/Information Sciences Institute, May
         1983.

[RFC861] Postel, J. and J. Reynolds, "Telnet Extended Options - List
         Option", STD 32, RFC 861, USC/Information Sciences Institute,
         May 1983.

[RFC885] Postel, J., "Telnet End of Record Option", RFC 885,
         USC/Information Sciences Institute, December 1983.

[RFC927] Anderson, B., "TACACS User Identification Telnet Option",
         RFC 927, BBN, December 1984.

[RFC933] Silverman, S., "Output Marking Telnet Option", RFC 933,
         MITRE, January 1985.

[RFC946] Nedved, R., "Telnet Terminal Location Number Option",
         RFC 946, Carnegie-Mellon University, May 1985.

[RDC1041] Rekhter, J., "Telnet 3270 Regime Option", RFC 1041,
          IBM, January 1988.

[RFC1043] Yasuda, A., and T. Thompson, "TELNET Data Entry Terminal
          Option DODIIS Implementation", RFC 1043, DIA, February 1988.

[RFC1053] Levy, S., and T. Jacobson, "Telnet X.3 PAD Option",
          RFC 1053, Minnesota Supercomputer Center, April 1988.

[RFC1073] Waitzman, D., "Telnet Window Size Option", RFC 1073,
          BBN STC, October, 1988.

[RFC1079] Hedrick, C., "Telnet Terminal Speed Option", RFC 1079,
          Rutgers University, December 1988.

[RFC1091] VanBokkelen, J., "Telnet Terminal Type Option",
          RFC 1091, FTP Software, Inc., February 1989.

[RFC1096] Marcy, G., "Telnet X Display Location Option", RFC 1096,
          Carnegie Mellon University, March 1989.

[RFC1184] Borman, D., Editor, "Telnet Linemode Option",
          RFC 1184, Cray Research, Inc., October 1990.

[RFC1372] Hedrick, C., and D. Borman, "Telnet Remote Flow Control
         Option", RFC 1372, Rutgers University, Cray Research, Inc.,
         October 1992.

[RFC1408] Borman, D., Editor, "Telnet Environment Option", RFC 1408,
          Cray Research, Inc., January 1993.

[RFC1411] Borman, D., Editor, "Telnet Authentication: Kerberos 
          Version 4", RFC 1411, Cray Research, Inc., January 1993.

[RFC1416] Borman, D., Editor, "Telnet Authentication Option", RFC
          1416, Cray Research, Inc., February 1993.

[RFC1572] Alexander, S., Editor, "Telnet Environment Option", RFC1572,
          Lachman Technology, Inc., January 1994.

[RFC1647] Kelly, B., "TN3270 Enhancements", RFC1647, Auburn
          University, July 1994.

[RFC2066] Gellens, R., "Telnet CharSet Option", RFC 2066, Unisys,
          January 1997.

[RFC2217] Clark, G., "Telnet Com Port Control Option", RFC 2217, 
          Cisco Systems, Inc., October 1997.

[RFC2840] Altman, J., "Telnet Kermit Option", RFC 2840, May 2000.

[RFC2941] Ts'o, T. and J. Altman, "Telnet Authentication Option",
          RFC 2941, September 2000.

[RFC2942] Ts'o, T., "Telnet Authentication: Kerberos Version 5",
          RFC 2942, September 2000.

[RFC2943] Housley, R., Horting, T. and P. Yee, "TELNET Authentication
          Using DSA", RFC 2943, September 2000.

[RFC2944] Wu, T., "Telnet Authentication: SRP", RFC 2944, September
          2000. 

[RFC2946] Ts'o, T., "Telnet Data Encryption Option", RFC 2946,
          September 2000.
 
[RFC2947] Altman, J., "Telnet Encryption: DES3 64 bit Cipher
          Feedback", RFC 2947, September 2000.

[RFC2948] Altman, J., "Telnet Encryption: DES3 64 bit Output
          Feedback", RFC 2948, September 2000.

[RFC2949] Altman, J., "Telnet Encryption: CAST-128 64 bit Output
          Feedback", RFC 2949, September 2000.

[RFC2950] Altman, J., "Telnet Encryption: CAST-128 64 bit Cipher
          Feedback", September 2000.   

[RFC2951] Housley, R., Horting, T. and P. Yee, "TELNET Authentication
          Using KEA and SKIPJACK", September 2000.

[RFC2952] Ts'o, T., "Telnet Encryption: DES 64 bit Cipher Feedback",
          RFC 2952, September 2000.

[RFC2953] Ts'o, T., "Telnet Encryption: DES 64 bit Output Feedback",
          RFC 2953, September 2000.

PEOPLE
------

[Altman] Jeffrey Altman, <jaltman@watsun.cc.columbia.edu>, August
         1998, January 2000.

[Atmar] Wirt Atmar, <atmar@aics-research.com>, June 1998.

[Barnes] Robert Barnes, <rab@stallion.oz.au>, July 1997.

[Boe] Michael Boe, <mboe@cisco.com>, June 1998.

[Brashear] Derrick Brashear, <shadow@dementia.org>, January 1995.

[Borman] Dave Borman, <dab@CRAY.COM>, January 1995.

[Croft] David Croft, <david@infotrek.co.uk>, September 1998.

[Earhart] Rob Earhart, <earhart+@CMU.EDU>, April 1995.

[Horting] Todd Horting <thorting@spyrus.com>, April 1998.

[Hudson] Tim Hudson <tjh@cryptsoft.com>, December 1998.

[IANA] Internet Assigned Numbers Authority, <iana@isi.edu>, January 1995.

[Josefsson] S. Josefsson <jas@extundo.com>, November 2003.
       http://josefsson.org/shishi/shishi.html#Telnet%20encryption%20with%20AES-CCM

[Kahn] Louis Kahn, <louisk@microsoft.com>, October 1998.

[McGregory] Steve McGregory <stevemc@pragmasys.com>, December 1998.

[Schoch]  Steven Schoch, <schoch@sheba.arc.nasa.gov>, January 1995.

[Ts'o] Theodore Ts'o, <tytso@mit.edu>, September 1998.

[Wu] Thomas Wu, <tjw@stanford.edu>, July 1997, September 1998.

[]

