Internet Assigned Numbers Authority Telnet Options Last Updated 2022-03-16 Available Formats [IMG] XML [IMG] HTML [IMG] Plain text Registries included below * Telnet Options * Telnet Authentication Types (Option 37) * Command * Types * KERBEROS_V4 Telnet Authentication Type (Type 1) * KERBEROS_V5 Telnet Authentication Type (Type 2) * SRP Telnet Authentication Type (Type 5) * KEA_SJ (Type 12) and KEA_SJ_INTEG (Type 13) Authentication Types * DSS Authentication Type (Type 14) * Telnet Encryption Types (Option 38) * Command * Types * DES_CFB64 Telnet Encryption Type (Type 1) * DES_OFB64 Telnet Encryption Type (Type 2) * DES3_CFB64 Telnet Encryption Type (Type 3) * DES3_OFB64 Telnet Encryption Type (Type 4) * CAST5_40_CFB64 (Type 8) and CAST128_CFB64 (Type 10) Telnet Encryption Types * CAST5_40_OFB64 (Type 9) and CAST128_OFB64 (Type 11) Telnet Encryption Types Telnet Options Registration Procedure(s) IETF Review Reference [RFC855] 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 [IMG] CSV Options Name Reference 0 Binary Transmission [RFC856] 1 Echo [RFC857] 2 Reconnection [NIC 15391 of 1973] 3 Suppress Go Ahead [RFC858] 4 Approx Message Size Negotiation [NIC 15393 of 1973] 5 Status [RFC859] 6 Timing Mark [RFC860] 7 Remote Controlled Trans and Echo [RFC726] 8 Output Line Width [NIC 20196 of August 1978] 9 Output Page Size [NIC 20197 of August 1978] 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 [RFC2355] 41 XAUTH [Rob_Earhart] 42 CHARSET [RFC2066] 43 Telnet Remote Serial Port (RSP) [Robert_Barnes] 44 Com Port Control Option [RFC2217] 45 Telnet Suppress Local Echo [Wirt_Atmar] 46 Telnet Start TLS [Michael_Boe] 47 KERMIT [RFC2840] 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 [RFC861] Telnet Authentication Types (Option 37) Registration Procedure(s) First Come First Served Reference [RFC2941] Command Registration Procedure(s) First Come First Served Reference [RFC2941] Available Formats [IMG] CSV Command Description Reference 0 IS [RFC2941] 1 SEND [RFC2941] 2 REPLY [RFC2941] 3 NAME [RFC2941] Types Registration Procedure(s) First Come First Served Reference [RFC2941] Available Formats [IMG] CSV Type Description Reference 0 NULL [RFC2941] 1 KERBEROS_V4 [RFC2941] 2 KERBEROS_V5 [RFC2942] 3 SPX [RFC2941][1] 4 MINK [RFC2941][1] 5 SRP [RFC2944] 6 RSA (also used by SRA) [RFC2941] 7 SSL [RFC2941] 8-9 Unassigned [IANA] 10 LOKI [RFC2941][1] 11 SSA [Steven_Schoch] 12 KEA_SJ [RFC2951] 13 KEA_SJ_INTEG [RFC2951] 14 DSS [RFC2943] 15 NTLM [Louis_Kahn][1] KERBEROS_V4 Telnet Authentication Type (Type 1) Registration Procedure(s) First Come First Served Reference [RFC1411] Available Formats [IMG] CSV Suboption Command Reference 0 AUTH [RFC1411] 1 REJECT [RFC1411] 2 ACCEPT [RFC1411] 3 CHALLENGE [RFC1411] 4 RESPONSE [RFC1411] 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 [RFC2942] Available Formats [IMG] CSV 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] SRP Telnet Authentication Type (Type 5) Registration Procedure(s) Specification Required Expert(s) Unassigned Reference [RFC2944] Available Formats [IMG] CSV 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] KEA_SJ (Type 12) and KEA_SJ_INTEG (Type 13) Authentication Types Registration Procedure(s) Specification Required Expert(s) Unassigned Reference [RFC2951] Available Formats [IMG] CSV 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] DSS Authentication Type (Type 14) Registration Procedure(s) Specification Required Expert(s) Unassigned Reference [RFC2943] Available Formats [IMG] CSV Suboption Command Reference 1 DSS_INITIALIZE [RFC2943] 2 DSS_TOKENBA [RFC2943] 3 DSS_CERTA_TOKENAB [RFC2943] 4 DSS_CERTB_TOKENBA2 [RFC2943] Telnet Encryption Types (Option 38) Registration Procedure(s) First Come First Served Reference [RFC2946] Note 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 registered by the IANA and documented here. Command Registration Procedure(s) First Come First Served Reference [RFC2946] Available Formats [IMG] CSV Command Description Reference 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] Types Registration Procedure(s) First Come First Served Reference [RFC2946] Available Formats [IMG] CSV Type Description Reference 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 [S_Josefsson] DES_CFB64 Telnet Encryption Type (Type 1) Registration Procedure(s) First Come First Served Reference [RFC2952] Available Formats [IMG] CSV Suboption Command Reference 1 CFB64_IV [RFC2952] 2 CFB64_IV_OK [RFC2952] 3 CFB64_IV_BAD [RFC2952] DES_OFB64 Telnet Encryption Type (Type 2) Registration Procedure(s) First Come First Served Reference [RFC2953] Available Formats [IMG] CSV Suboption Command Reference 1 OFB64_IV [RFC2953] 2 OFB64_IV_OK [RFC2953] 3 OFB64_IV_BAD [RFC2953] DES3_CFB64 Telnet Encryption Type (Type 3) Registration Procedure(s) First Come First Served Reference [RFC2947] Available Formats [IMG] CSV Suboption Command Reference 1 CFB64_IV [RFC2947] 2 CFB64_IV_OK [RFC2947] 3 CFB64_IV_BAD [RFC2947] DES3_OFB64 Telnet Encryption Type (Type 4) Registration Procedure(s) First Come First Served Reference [RFC2948] Available Formats [IMG] CSV Suboption Command Reference 1 OFB64_IV [RFC2948] 2 OFB64_IV_OK [RFC2948] 3 OFB64_IV_BAD [RFC2948] CAST5_40_CFB64 (Type 8) and CAST128_CFB64 (Type 10) Telnet Encryption Types Registration Procedure(s) First Come First Served Reference [RFC2950] Available Formats [IMG] CSV Suboption Command Reference 1 CFB64_IV [RFC2950] 2 CFB64_IV_OK [RFC2950] 3 CFB64_IV_BAD [RFC2950] CAST5_40_OFB64 (Type 9) and CAST128_OFB64 (Type 11) Telnet Encryption Types Registration Procedure(s) First Come First Served Reference [RFC2949] Available Formats [IMG] CSV Suboption Command Reference 1 OFB64_IV [RFC2949] 2 OFB64_IV_OK [RFC2949] 3 OFB64_IV_BAD [RFC2949] 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:louiskµsoft.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 2003-11 http://josefsson.org/shishi/shishi.html#Telnet%20encryption%20with%20AES-CCM [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. Licensing Terms