Telnet Options

Registration Procedure(s)

IETF Review

Reference

[RFC 855]

Note

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.

Available Formats

CSV

Options	Name	Reference
0	Binary Transmission	[RFC 856]
1	Echo	[RFC 857]
2	Reconnection	[NIC 15391 of 1973]
3	Suppress Go Ahead	[RFC 858]
4	Approx Message Size Negotiation	[NIC 15393 of 1973]
5	Status	[RFC 859]
6	Timing Mark	[RFC 860]
7	Remote Controlled Trans and Echo	[RFC 726]
8	Output Line Width	[NIC 20196 of August 1978]
9	Output Page Size	[NIC 20197 of August 1978]
10	Output Carriage-Return Disposition	[RFC 652]
11	Output Horizontal Tab Stops	[RFC 653]
12	Output Horizontal Tab Disposition	[RFC 654]
13	Output Formfeed Disposition	[RFC 655]
14	Output Vertical Tabstops	[RFC 656]
15	Output Vertical Tab Disposition	[RFC 657]
16	Output Linefeed Disposition	[RFC 658]
17	Extended ASCII	[RFC 698]
18	Logout	[RFC 727]
19	Byte Macro	[RFC 735]
20	Data Entry Terminal	[RFC 1043][RFC 732]
21	SUPDUP	[RFC 736][RFC 734]
22	SUPDUP Output	[RFC 749]
23	Send Location	[RFC 779]
24	Terminal Type	[RFC 1091]
25	End of Record	[RFC 885]
26	TACACS User Identification	[RFC 927]
27	Output Marking	[RFC 933]
28	Terminal Location Number	[RFC 946]
29	Telnet 3270 Regime	[RFC 1041]
30	X.3 PAD	[RFC 1053]
31	Negotiate About Window Size	[RFC 1073]
32	Terminal Speed	[RFC 1079]
33	Remote Flow Control	[RFC 1372]
34	Linemode	[RFC 1184]
35	X Display Location	[RFC 1096]
36	Environment Option	[RFC 1408]
37	Authentication Option	[RFC 2941]
38	Encryption Option	[RFC 2946]
39	New Environment Option	[RFC 1572]
40	TN3270E	[RFC 2355]
41	XAUTH	[Rob_Earhart]
42	CHARSET	[RFC 2066]
43	Telnet Remote Serial Port (RSP)	[Robert_Barnes]
44	Com Port Control Option	[RFC 2217]
45	Telnet Suppress Local Echo	[Wirt_Atmar]
46	Telnet Start TLS	[Michael_Boe]
47	KERMIT	[RFC 2840]
48	SEND-URL	[David_Croft]
49	FORWARD_X	[Jeffrey_Altman]
50-137	Unassigned	[IANA]
138	TELOPT PRAGMA LOGON	[Steve_McGregory]
139	TELOPT SSPI LOGON	[Steve_McGregory]
140	TELOPT PRAGMA HEARTBEAT	[Steve_McGregory]
141-254	Unassigned
255	Extended-Options-List	[RFC 861]

Telnet Authentication Types (Option 37)

Registration Procedure(s)

First Come First Served

Reference

[RFC 2941]

Command

Registration Procedure(s)

First Come First Served

Reference

[RFC 2941]

Available Formats

CSV

Command	Description	Reference
0	IS	[RFC 2941]
1	SEND	[RFC 2941]
2	REPLY	[RFC 2941]
3	NAME	[RFC 2941]

Types

Registration Procedure(s)

First Come First Served

Reference

[RFC 2941]

Available Formats

CSV

Type	Description	Reference
0	NULL	[RFC 2941]
1	KERBEROS_V4	[RFC 2941]
2	KERBEROS_V5	[RFC 2942]
3	SPX	[RFC 2941][1]
4	MINK	[RFC 2941][1]
5	SRP	[RFC 2944]
6	RSA (also used by SRA)	[RFC 2941]
7	SSL	[RFC 2941]
8-9	Unassigned	[IANA]
10	LOKI	[RFC 2941][1]
11	SSA	[Steven_Schoch]
12	KEA_SJ	[RFC 2951]
13	KEA_SJ_INTEG	[RFC 2951]
14	DSS	[RFC 2943]
15	NTLM	[Louis_Kahn][1]

KERBEROS_V4 Telnet Authentication Type (Type 1)

Registration Procedure(s)

First Come First Served

Reference

[RFC 1411]

Available Formats

CSV

Suboption	Command	Reference
0	AUTH	[RFC 1411]
1	REJECT	[RFC 1411]
2	ACCEPT	[RFC 1411]
3	CHALLENGE	[RFC 1411]
4	RESPONSE	[RFC 1411]
5	FORWARD	[Derrick_Brashear]
6	FORWARD-ACCEPT	[Derrick_Brashear]
7	FORWARD-REJECT	[Derrick_Brashear]
8	EXP	[Thomas_Wu]
9	PARAMS	[Thomas_Wu]

KERBEROS_V5 Telnet Authentication Type (Type 2)

Registration Procedure(s)

Specification Required

Expert(s)

Unassigned

Reference

[RFC 2942]

Available Formats

CSV

Suboption	Command	Reference
0	AUTH	[RFC 2942]
1	REJECT	[RFC 2942]
2	ACCEPT	[RFC 2942]
3	RESPONSE	[RFC 2942]
4	FORWARD	[RFC 2942]
5	FORWARD_ACCEPT	[RFC 2942]
6	FORWARD-REJECT	[RFC 2942]

SRP Telnet Authentication Type (Type 5)

Registration Procedure(s)

Specification Required

Expert(s)

Unassigned

Reference

[RFC 2944]

Available Formats

CSV

Suboption	Command	Reference
0	AUTH	[RFC 2944]
1	REJECT	[RFC 2944]
2	ACCEPT	[RFC 2944]
3	CHALLENGE	[RFC 2944]
4	RESPONSE	[RFC 2944]
5-7	Unassigned	[RFC 2944]
8	EXP	[RFC 2944]
9	PARAMS	[RFC 2944]

KEA_SJ (Type 12) and KEA_SJ_INTEG (Type 13) Authentication Types

Registration Procedure(s)

Specification Required

Expert(s)

Unassigned

Reference

[RFC 2951]

Available Formats

CSV

Suboption	Command	Reference
1	KEA_CERTA_RA	[RFC 2951]
2	KEA_CERTB_RB_IVB_NONCEB	[RFC 2951]
3	KEA_IVA_RESPONSEB_NONCEA	[RFC 2951]
4	KEA_RESPONSEA	[RFC 2951]

DSS Authentication Type (Type 14)

Registration Procedure(s)

Specification Required

Expert(s)

Unassigned

Reference

[RFC 2943]

Available Formats

CSV

Suboption	Command	Reference
1	DSS_INITIALIZE	[RFC 2943]
2	DSS_TOKENBA	[RFC 2943]
3	DSS_CERTA_TOKENAB	[RFC 2943]
4	DSS_CERTB_TOKENBA2	[RFC 2943]

Telnet Encryption Types (Option 38)

Registration Procedure(s)

First Come First Served

Reference

[RFC 2946]

Note

In the Telnet Encryption commands and types [RFC 2946] 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
registered by the IANA and documented here.

Command

Registration Procedure(s)

First Come First Served

Reference

[RFC 2946]

Available Formats

CSV

Command	Description	Reference
0	IS	[RFC 2946]
1	SUPPORT	[RFC 2946]
2	REPLY	[RFC 2946]
3	START	[RFC 2946]
4	END	[RFC 2946]
5	REQUEST-START	[RFC 2946]
6	REQUEST-END	[RFC 2946]
7	ENC_KEYID	[RFC 2946]
8	DEC_KEYID	[RFC 2946]

Types

Registration Procedure(s)

First Come First Served

Reference

[RFC 2946]

Available Formats

CSV

Type	Description	Reference
0	NULL	[RFC 2946]
1	DES_CFB64	[RFC 2946]
2	DES_OFB64	[RFC 2946]
3	DES3_CFB64	[RFC 2946]
4	DES3_OFB64	[RFC 2946]
5-7	Unassigned	[IANA]
8	CAST5_40_CFB64	[RFC 2946]
9	CAST5_40_OFB64	[RFC 2946]
10	CAST128_CFB64	[RFC 2946]
11	CAST128_OFB64	[RFC 2946]
12	AES_CCM	[S_Josefsson]

DES_CFB64 Telnet Encryption Type (Type 1)

Registration Procedure(s)

First Come First Served

Reference

[RFC 2952]

Available Formats

CSV

Suboption	Command	Reference
1	CFB64_IV	[RFC 2952]
2	CFB64_IV_OK	[RFC 2952]
3	CFB64_IV_BAD	[RFC 2952]

DES_OFB64 Telnet Encryption Type (Type 2)

Registration Procedure(s)

First Come First Served

Reference

[RFC 2953]

Available Formats

CSV

Suboption	Command	Reference
1	OFB64_IV	[RFC 2953]
2	OFB64_IV_OK	[RFC 2953]
3	OFB64_IV_BAD	[RFC 2953]

DES3_CFB64 Telnet Encryption Type (Type 3)

Registration Procedure(s)

First Come First Served

Reference

[RFC 2947]

Available Formats

CSV

Suboption	Command	Reference
1	CFB64_IV	[RFC 2947]
2	CFB64_IV_OK	[RFC 2947]
3	CFB64_IV_BAD	[RFC 2947]

DES3_OFB64 Telnet Encryption Type (Type 4)

Registration Procedure(s)

First Come First Served

Reference

[RFC 2948]

Available Formats

CSV

Suboption	Command	Reference
1	OFB64_IV	[RFC 2948]
2	OFB64_IV_OK	[RFC 2948]
3	OFB64_IV_BAD	[RFC 2948]

CAST5_40_CFB64 (Type 8) and CAST128_CFB64 (Type 10) Telnet Encryption Types

Registration Procedure(s)

First Come First Served

Reference

[RFC 2950]

Available Formats

CSV

Suboption	Command	Reference
1	CFB64_IV	[RFC 2950]
2	CFB64_IV_OK	[RFC 2950]
3	CFB64_IV_BAD	[RFC 2950]

CAST5_40_OFB64 (Type 9) and CAST128_OFB64 (Type 11) Telnet Encryption Types

Registration Procedure(s)

First Come First Served

Reference

[RFC 2949]

Available Formats

CSV

Suboption	Command	Reference
1	OFB64_IV	[RFC 2949]
2	OFB64_IV_OK	[RFC 2949]
3	OFB64_IV_BAD	[RFC 2949]

Contact Information

ID	Name	Contact URI	Last Updated
[David_Croft]	David Croft	mailto:david&infotrek.co.uk	1998-09
[Derrick_Brashear]	Derrick Brashear	mailto:shadow&dementia.org	1995-01
[IANA]	Internet Assigned Numbers Authority	mailto:iana&iana.org	2012-08
[Jeffrey_Altman]	Jeffrey Altman	mailto:jaltman&watsun.cc.columbia.edu	2000-01
[Louis_Kahn]	Louis Kahn	mailto:louisk&microsoft.com	1998-10
[Michael_Boe]	Michael Boe	mailto:mboe&cisco.com	1998-06
[Rob_Earhart]	Rob Earhart	mailto:earhart+&cmu.edu	1995-04
[Robert_Barnes]	Robert Barnes	mailto:rab&stallion.oz.au	1997-07
[S_Josefsson]	S. Josefsson	mailto:jas&extundo.com http://josefsson.org/shishi/shishi.html#Telnet%20encryption%20with%20AES-CCM	2003-11
[Steve_McGregory]	Steve McGregory	mailto:stevemc&pragmasys.com	1998-12
[Steven_Schoch]	Steven Schoch	mailto:schoch&sheba.arc.nasa.gov	1995-01
[Thomas_Wu]	Thomas Wu	mailto:tjw&stanford.edu	1998-09
[Wirt_Atmar]	Wirt Atmar	mailto:atmar&aics-research.com	1998-06

Footnote

[1]	Authentication types never submitted to the IETF for consideration as an Internet standard.