While transferring protocol data, special Telnet commands are intertwined with the data to allow the client and server devices to perform various functions needed to manage the operation of the protocol.
This is the list of commands:
| Code | HEX code | Name | Description |
|---|---|---|---|
| 240 | F0 | SE | End of subnegotiation parameters. |
| 241 | F1 | NOP | No operation. |
| 242 | F2 | Data Mark | The data stream portion of a Synch. This should always be accompanied by a TCP Urgent notification. |
| 243 | F3 | Break | NVT character BRK. |
| 244 | F4 | Interrupt Process | The function IP. |
| 245 | F5 | Abort output | The function AO. |
| 246 | F6 | Are You There | The function AYT. |
| 247 | F7 | Erase character | The function EC. |
| 248 | F8 | Erase Line | The function EL. |
| 249 | F9 | Go ahead | The GA signal. |
| 250 | FA | SB | Indicates that what follows is subnegotiation of the indicated option. |
| 251 | FB | WILL (option code) | Indicates the desire to begin performing, or confirmation that you are now performing, the indicated option. |
| 252 | FC | WON'T (option code) | Indicates the refusal to perform, or continue performing, the indicated option. |
| 253 | FD | 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 | FE | 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 | FF | IAC | Interpret as command: beginning of a command. |