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.
Table 1. Telnet commands from 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.
Table 2. Telnet command options
from RFC 1060
| 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 |