Telnet commands and options
For information about Telnet connection negotiations,
see RFC 2355. Table 1 describes the Telnet
commands from RFC 854, when the codes and code sequences are preceded
by an IAC. For more information about Telnet commands, see RFC 854.
Command | Code | Description |
---|---|---|
SE | X'F0' | End of subnegotiation parameters. |
NOP | X'F1' | No operation. |
Data Mark | X'F2' | The data stream portion of a Synch. This should always be accompanied by a TCP Urgent notification. |
Break | X'F3' | NVT character BRK. |
Interrupt Process | X'F4' | The function IP. |
Abort output | X'F5' | The function AO. |
Are You There | X'F6' | The function AYT. |
Erase character | X'F7' | The function EC. |
Erase Line | X'F8' | The function EL. |
Go ahead | X'F9' | The GA signal. |
SB | X'FA' | Indicates that what follows is subnegotiation of the indicated option. |
WILL (option code) | X'FB' | Indicates the want to begin performing, or confirmation that you are now performing, the indicated option. |
WON'T (option code) | X'FC' | Indicates the refusal to perform, or continue performing, the indicated option. |
DO (option code) | X'FD' | Indicates the request that the other party perform, or confirmation that you are expecting the other party to perform, the indicated option. |
DON'T (option code) | X'FE' | 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. |
IAC | X'FF' | Data byte 255. |
Table 2 lists the options available for Telnet commands from RFC 1060. For more information about Telnet protocols, see RFC 1060 and RFC 1011.
Option | Option (Hex) | Name |
---|---|---|
0 | 0 | Binary Transmission |
1 | 1 | Echo |
2 | 2 | Reconnection |
3 | 3 | Suppress Go Ahead |
4 | 4 | Approx Message Size Negotiation |
5 | 5 | Status |
6 | 6 | Timing Mark |
7 | 7 | Remote Controlled Trans and Echo |
8 | 8 | Output Line Width |
9 | 9 | Output Page Size |
10 | A | Output Carriage-Return Disposition |
11 | B | Output Horizontal Tab Stops |
12 | C | Output Horizontal Tab Disposition |
13 | D | Output Formfeed Disposition |
14 | E | Output Vertical Tabstops |
15 | F | Output Vertical Tab Disposition |
16 | 10 | Output Linefeed Disposition |
17 | 11 | Extended ASCII |
18 | 12 | Logout |
19 | 13 | Byte Macro |
20 | 14 | Data Entry Terminal |
21 | 15 | SUPDUP |
22 | 16 | SUPDUP Output |
23 | 17 | Send Location |
24 | 18 | Terminal Type |
25 | 19 | End of Record |
26 | 1A | TACACS User Identification |
27 | 1B | Output Marking |
28 | 1C | Terminal Location Number |
29 | 1D | Telnet 3270 Regime |
30 | 1E | X.3 PAD |
31 | 1F | Negotiate About Window Size |
32 | 20 | Terminal Speed |
33 | 21 | Remote Flow Control |
34 | 22 | Linemode |
35 | 23 | X Display Location |
255 | FF | Extended-Options-List |