| Telnet |
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Description | Glossary | RFCs | Publications | Obsolete RFCs |
| Protocol suite: | TCP/IP. |
| Protocol type: | Application layer terminal protocol. |
| Ports: | 23 (TCP) server; 107 (TCP) Remote User Telnet. |
| URI: | telnet: |
| SNMP MIBs: | |
| Working groups: |
telnet, telnet. tn3270e, Telnet TN3270 Enhancements. |
| Links: |
IANA: Telnet options. telnet.org |
The Telnet protocol defines an interactive, text based communications session between a client and a host.
| MAC header | IP header | TCP header | Telnet message |
Telnet commands:
| Code | Name | Description |
|---|---|---|
| 240 | SE | End of subnegotiation parameters. |
| 241 | NOP | No operation. |
| 242 | Data Mark | The data stream portion of a Synch. This should always be accompanied by a TCP Urgent notification. |
| 243 | Break | NVT character BRK. |
| 244 | Interrupt Process | The function IP. |
| 245 | Abort output | The function AO. |
| 246 | Are You There | The function AYT. |
| 247 | Erase character | The function EC. |
| 248 | Erase Line | The function EL. |
| 249 | Go ahead | The GA signal. |
| 250 | SB | Indicates that what follows is subnegotiation of the indicated option. |
| 251 | WILL (option code) | Indicates the desire to begin performing, or confirmation that you are now performing, the indicated option. |
| 252 | WON'T (option code) | Indicates the refusal to perform, or continue performing, the indicated option. |
| 253 | DO (option code) | Indicates the request that the other party perform, or confirmation that you are expecting the other party to perform, the indicated option. |
| 254 | DON'T (option code) | Indicates the demand that the other party stop performing, or confirmation that you are no longer expecting the other party to perform, the indicated option. |
| 255 | IAC | Data Byte 255. |
Telnet options:
| Code | Option | References |
|---|---|---|
| 0 | TRANSMIT-BINARY, Binary Transmission. | RFC 856 |
| 1 | ECHO, Echo. | RFC 857 |
| 2 | Reconnection. | |
| 3 | SUPPRESS-GO-AHEAD, Suppress Go Ahead. | RFC 858 |
| 4 | Approx Message Size Negotiation. | |
| 5 | STATUS. | RFC 859 |
| 6 | TIMING-MARK, Timing Mark | RFC 860 |
| 7 | RCTE, Remote Controlled Trans and Echo. | RFC 563, RFC 581, RFC 726 |
| 8 | Output Line Width. | |
| 9 | Output Page Size. | |
| 10 | NAOCRD, Negotiate About Output Carriage-Return Disposition. | RFC 652 |
| 11 | NAOHTS, Negotiate About Output Horizontal Tabstops. | RFC 653 |
| 12 | NAOHTD, Negotiate About Output Horizontal Tab Disposition. | RFC 654 |
| 13 | NAOFFD, Negotiate About Output Formfeed Disposition. | RFC 655 |
| 14 | NAOVTS, Negotiate About Vertical Tabstops. | RFC 656 |
| 15 | NAOVTD, Negotiate About Output Vertcial Tab Disposition. | RFC 657 |
| 16 | NAOLFD, Negotiate About Output Linefeed Disposition. | RFC 658. |
| 17 | Extended ASCII. | RFC 698 |
| 18 | LOGOUT, Logout. | RFC 727 |
| 19 | BM, Byte Macro. | RFC 735 |
| 20 | Data Entry Terminal. | RFC 732, RFC 1043 |
| 21 | SUPDUP. | RFC 734, RFC 736 |
| 22 | SUPDUP-OUTPUT, SUPDUP Output. | RFC 749 |
| 23 | SEND-LOCATION, Send Location. | RFC 779 |
| 24 | TERMINAL-TYPE, Terminal Type. | RFC 1091 |
| 25 | END-OF-RECORD, End of Record. | RFC 885 |
| 26 | TUID, TACACS User Identification. | RFC 927 |
| 27 | OUTMRK, Output Marking. | RFC 933 |
| 28 | TTYLOC, Terminal Location Number. | RFC 946 |
| 29 | Telnet 3270 Regime. | RFC 1041 |
| 30 | X.3 PAD. | RFC 1053 |
| 31 | NAWS, 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, Authentication Option. | RFC 1416, RFC 2941, RFC 2942, RFC 2943, RFC 2951 |
| 38 | Encryption Option. | RFC 2946 |
| 39 | New Environment Option. | RFC 1572 |
| 40 | TN3270E. | RFC 2355 |
| 41 | XAUTH. | |
| 42 | CHARSET. | RFC 2066 |
| 43 | RSP, Telnet Remote Serial Port. | |
| 44 | Com Port Control Option | RFC 2217 |
| 45 | Telnet Suppress Local Echo | |
| 46 | Telnet Start TLS | |
| 47 | KERMIT | RFC 2840 |
| 48 | SEND-URL | |
| 49 | FORWARD_X | |
| 50 - 137 | ||
| 138 | TELOPT PRAGMA LOGON | |
| 139 | TELOPT SSPI LOGON | |
| 140 | TELOPT PRAGMA HEARTBEAT | |
| 141 - 254 | ||
| 255 | EXOPL, Extended-Options-List. | RFC 861 |
RFCs:
[RFC 97] A First Cut at a Proposed Telnet Protocol.
[RFC 137] TELNET Protocol.
[RFC 139] Discussion of TELNET Protocol.
[RFC 158] Proposed Telnet Protocol.
[RFC 318] Telnet Protocol.
[RFC 328] Suggested Telnet Protocol Changes.
[RFC 340] PROPOSED TELNET CHANGES.
[RFC 393] Comments on TELNET Protocol Changes.
[RFC 435] TELNET Issues.
[RFC 452] Telnet Command at Host LL.
[RFC 495] TELNET Protocol Specification.
[RFC 513] COMMENTS ON THE NEW TELNET SPECIFICATIONS.
[RFC 529] A Note on Protocol Synch Sequences.
[RFC 559] Comments on the new TELNET Protocol and its Implementation.
[RFC 560] Remote Controlled Transmission and Echoing Telnet Option.
[RFC 562] Modifications to the Telnet Specification.
[RFC 563] Comments on the RCTE TELNET Option.
[RFC 581] Corrections to RFC 560 - Remote Controlled Transmission and Echoing Telnet Option.
[RFC 587] Announcing New Telnet Options.
[RFC 593] Telnet and FTP Implementation Schedule Change.
[RFC 595] Some Thoughts in Defense of the TELNET Go-Ahead.
[RFC 596] Second Thoughts on Telnet Go-Ahead.
[RFC 652] Telnet Output Carriage-Return Disposition Option.
[RFC 653] TELNET OUTPUT HORIZONTAL TABSTOPS OPTION.
[RFC 654] TELNET OUTPUT HORIZONTAL TAB DISPOSITION OPTION.
[RFC 655] TELNET OUTPUT FORMFEED DISPOSITION OPTION.
[RFC 656] TELNET OUTPUT VERTICAL TABSTOPS OPTION.
[RFC 657] TELNET OUTPUT VERTICAL TAB DISPOSITION OPTION.
[RFC 658] TELNET OUTPUT LINEFEED DISPOSITION.
[RFC 659] Announcing Addtional Telnet Options.
[RFC 669] November, 1974, Survey of New-Protocol TELNET Servers.
[RFC 671] A Note on Reconnection Protocol.
[RFC 679] February, 1975, Survey of New-Protocol Telnet Servers.
[RFC 698] TELNET EXTENDED ASCII OPTION.
[RFC 701] AUGUST, 1974, SURVEY OF NEW-PROTOCOL TELNET SERVERS.
[RFC 702] SEPTEMBER, 1974, SURVEY OF NEW-PROTOCOL TELNET SERVERS.
[RFC 703] July, 1975, Survey of New-Protocol TELNET Servers.
[RFC 718] Comments on RCTE from the TENEX Implementation Experience.
[RFC 719] Discussion on RCTE.
[RFC 726] Remote Controlled Transmssion and Echoing Telnet Option.
[RFC 727] TELNET Logout Option.
[RFC 728] A Minor Pitfall in the Telnet Protocol.
[RFC 732] Telnet Data Entry Terminal Option.
[RFC 734] SUPDUP Protocol.
[RFC 735] Revised TELNET Byte Macro Option.
[RFC 736] TELNET SUPDUP Option.
[RFC 749] Telnet SUPDUP-OUTPUT Option.
[RFC 779] TELNET SEND-LOCATION Option.
[RFC 818] The Remote User Telnet Service.
[RFC 854] TELNET Protocol Specification.
[RFC 855] TELNET Option Specifications.
[RFC 856] TELNET BINARY TRANSMISSION.
[RFC 857] TELNET ECHO OPTION.
[RFC 858] TELNET SUPPRESS GO AHEAD OPTION.
[RFC 859] TELNET STATUS OPTION.
[RFC 860] TELNET TIMING MARK OPTION.
[RFC 861] TELNET EXTENDED OPTIONS - LIST OPTION.
[RFC 885] TELNET END OF RECORD OPTION.
[RFC 927] TACACS User Identification Telnet Option.
[RFC 933] OUTPUT MARKING TELNET OPTION.
[RFC 946] TELNET TERMINAL LOCATION NUMBER OPTION.
[RFC 1041] Telnet 3270 Regime Option.
[RFC 1043] TELNET Data Entry Terminal Option DODIIS Implementation.
[RFC 1053] Telnet X.3 PAD Option.
[RFC 1073] Telnet Window Size Option.
[RFC 1079] Telnet Terminal Speed Option.
[RFC 1091] Telnet Terminal-Type Option.
[RFC 1096] Telnet X Display Location Option.
[RFC 1123] Requirements for Internet Hosts -- Application and Support.
[RFC 1143] The Q Method of Implementing TELNET Option Negotiation.
[RFC 1184] Telnet Linemode Option.
[RFC 1205] 5250 Telnet Interface.
[RFC 1372] Telnet Remote Flow Control Option.
[RFC 1408] Telnet Environment Option.
[RFC 1411] Telnet Authentication: Kerberos Version 4.
[RFC 1412] Telnet Authentication: SPX.
[RFC 1571] Telnet Environment Option Interoperability Issues.
[RFC 1572] Telnet Environment Option.
[RFC 1576] TN3270 Current Practices.
[RFC 1646] TN3270 Extensions for LUname and Printer Selection.
[RFC 1921] TNVIP Protocol.
[RFC 2066] TELNET CHARSET Option.
[RFC 2217] Telnet Com Port Control Option.
[RFC 2355] TN3270 Enhancements.
[RFC 2839] Internet Kermit Service.
[RFC 2840] TELNET KERMIT OPTION.
[RFC 2877] 5250 Telnet Enhancements.
[RFC 2941] Telnet Authentication Option.
[RFC 2942] Telnet Authentication: Kerberos Version 5.
[RFC 2943] TELNET Authentication Using DSA.
[RFC 2944] Telnet Authentication: SRP.
[RFC 2946] Telnet Data Encryption Option.
[RFC 2947] Telnet Encryption: DES3 64 bit Cipher Feedback.
[RFC 2948] Telnet Encryption: DES3 64 bit Output Feedback.
[RFC 2949] Telnet Encryption: CAST-128 64 bit Output Feedback.
[RFC 2950] Telnet Encryption: CAST-128 64 bit Cipher Feedback.
[RFC 2951] TELNET Authentication Using KEA and SKIPJACK.
[RFC 2952] Telnet Encryption: DES 64 bit Cipher Feedback.
[RFC 2953] Telnet Encryption: DES 64 bit Output Feedback.
[RFC 4248] The telnet URI Scheme.
[RFC 651] Revised Telnet Status Option.
[RFC 729] TELNET Byte Macro Option.
[RFC 731] Telnet Data Entry Terminal Option.
[RFC 764] TELNET PROTOCOL SPECIFICATION.
[RFC 884] TELNET TERMINAL TYPE OPTION.
[RFC 930] TELNET TERMINAL TYPE OPTION.
[RFC 1080] Telnet Remote Flow Control Option.
[RFC 1116] Telnet Linemode Option.
[RFC 1409] Telnet Authentication Option.
[RFC 1416] Telnet Authentication Option.
[RFC 1647] TN3270 Enhancements.
[RFC 1738] Uniform Resource Locators (URL).
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Description | Glossary | RFCs | Publications | Obsolete RFCs |