Telnet Options 2022-03-16 Telnet Options IETF Review 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. 0 Binary Transmission 1 Echo 2 Reconnection NIC 15391 of 1973 3 Suppress Go Ahead 4 Approx Message Size Negotiation NIC 15393 of 1973 5 Status 6 Timing Mark 7 Remote Controlled Trans and Echo 8 Output Line Width NIC 20196 of August 1978 9 Output Page Size NIC 20197 of August 1978 10 Output Carriage-Return Disposition 11 Output Horizontal Tab Stops 12 Output Horizontal Tab Disposition 13 Output Formfeed Disposition 14 Output Vertical Tabstops 15 Output Vertical Tab Disposition 16 Output Linefeed Disposition 17 Extended ASCII 18 Logout 19 Byte Macro 20 Data Entry Terminal 21 SUPDUP 22 SUPDUP Output 23 Send Location 24 Terminal Type 25 End of Record 26 TACACS User Identification 27 Output Marking 28 Terminal Location Number 29 Telnet 3270 Regime 30 X.3 PAD 31 Negotiate About Window Size 32 Terminal Speed 33 Remote Flow Control 34 Linemode 35 X Display Location 36 Environment Option 37 Authentication Option 38 Encryption Option 39 New Environment Option 40 TN3270E 41 XAUTH 42 CHARSET 43 Telnet Remote Serial Port (RSP) 44 Com Port Control Option 45 Telnet Suppress Local Echo 46 Telnet Start TLS 47 KERMIT 48 SEND-URL 49 FORWARD_X 50-137 Unassigned 138 TELOPT PRAGMA LOGON 139 TELOPT SSPI LOGON 140 TELOPT PRAGMA HEARTBEAT 141-254 Unassigned 255 Extended-Options-List Telnet Authentication Types (Option 37) First Come First Served Command First Come First Served 0 IS 1 SEND 2 REPLY 3 NAME Types First Come First Served 0 NULL 1 KERBEROS_V4 2 KERBEROS_V5 3 SPX 4 MINK 5 SRP 6 RSA (also used by SRA) 7 SSL 8-9 Unassigned 10 LOKI 11 SSA 12 KEA_SJ 13 KEA_SJ_INTEG 14 DSS 15 NTLM Authentication types never submitted to the IETF for consideration as an Internet standard. KERBEROS_V4 Telnet Authentication Type (Type 1) First Come First Served 0 AUTH 1 REJECT 2 ACCEPT 3 CHALLENGE 4 RESPONSE 5 FORWARD 6 FORWARD-ACCEPT 7 FORWARD-REJECT 8 EXP 9 PARAMS KERBEROS_V5 Telnet Authentication Type (Type 2) Specification Required Unassigned 0 AUTH 1 REJECT 2 ACCEPT 3 RESPONSE 4 FORWARD 5 FORWARD_ACCEPT 6 FORWARD-REJECT SRP Telnet Authentication Type (Type 5) Specification Required Unassigned 0 AUTH 1 REJECT 2 ACCEPT 3 CHALLENGE 4 RESPONSE 5-7 Unassigned 8 EXP 9 PARAMS KEA_SJ (Type 12) and KEA_SJ_INTEG (Type 13) Authentication Types Specification Required Unassigned 1 KEA_CERTA_RA 2 KEA_CERTB_RB_IVB_NONCEB 3 KEA_IVA_RESPONSEB_NONCEA 4 KEA_RESPONSEA DSS Authentication Type (Type 14) Specification Required Unassigned 1 DSS_INITIALIZE 2 DSS_TOKENBA 3 DSS_CERTA_TOKENAB 4 DSS_CERTB_TOKENBA2 Telnet Encryption Types (Option 38) First Come First Served In the Telnet Encryption commands and types 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 First Come First Served 0 IS 1 SUPPORT 2 REPLY 3 START 4 END 5 REQUEST-START 6 REQUEST-END 7 ENC_KEYID 8 DEC_KEYID Types First Come First Served 0 NULL 1 DES_CFB64 2 DES_OFB64 3 DES3_CFB64 4 DES3_OFB64 5-7 Unassigned 8 CAST5_40_CFB64 9 CAST5_40_OFB64 10 CAST128_CFB64 11 CAST128_OFB64 12 AES_CCM DES_CFB64 Telnet Encryption Type (Type 1) First Come First Served 1 CFB64_IV 2 CFB64_IV_OK 3 CFB64_IV_BAD DES_OFB64 Telnet Encryption Type (Type 2) First Come First Served 1 OFB64_IV 2 OFB64_IV_OK 3 OFB64_IV_BAD DES3_CFB64 Telnet Encryption Type (Type 3) First Come First Served 1 CFB64_IV 2 CFB64_IV_OK 3 CFB64_IV_BAD DES3_OFB64 Telnet Encryption Type (Type 4) First Come First Served 1 OFB64_IV 2 OFB64_IV_OK 3 OFB64_IV_BAD CAST5_40_CFB64 (Type 8) and CAST128_CFB64 (Type 10) Telnet Encryption Types First Come First Served 1 CFB64_IV 2 CFB64_IV_OK 3 CFB64_IV_BAD CAST5_40_OFB64 (Type 9) and CAST128_OFB64 (Type 11) Telnet Encryption Types First Come First Served 1 OFB64_IV 2 OFB64_IV_OK 3 OFB64_IV_BAD David Croft mailto:david&infotrek.co.uk 1998-09 Derrick Brashear mailto:shadow&dementia.org 1995-01 Internet Assigned Numbers Authority mailto:iana&iana.org 2012-08 Jeffrey Altman mailto:jaltman&watsun.cc.columbia.edu 2000-01 Louis Kahn mailto:louisk&microsoft.com 1998-10 Michael Boe mailto:mboe&cisco.com 1998-06 Rob Earhart mailto:earhart+&cmu.edu 1995-04 Robert Barnes mailto:rab&stallion.oz.au 1997-07 S. Josefsson mailto:jas&extundo.com http://josefsson.org/shishi/shishi.html#Telnet%20encryption%20with%20AES-CCM 2003-11 Steve McGregory mailto:stevemc&pragmasys.com 1998-12 Steven Schoch mailto:schoch&sheba.arc.nasa.gov 1995-01 Thomas Wu mailto:tjw&stanford.edu 1998-09 Wirt Atmar mailto:atmar&aics-research.com 1998-06