Negotiate About Window Size (NAWS)
Option code: 31
See also: RFC 1073
When enabled, this Telnet option requests that the client immediately sends a telnet subnegotiation containing the current screen size (in characters) and later on every time the size changes.
Usually it is the server that sends a IAC DO NAWS to toggle that behavior.
| Tokens | Bytes | Meaning |
|---|---|---|
| IAC WILL NAWS | 255 251 31 | Client: I will/would like to send NAWS messages |
| IAC WONT NAWS | 255 252 31 | Client: I won't send NAWS messages |
| IAC DO NAWS | 255 253 31 | Server: Hey client, please send NAWS messages |
| IAC DONT NAWS | 255 254 31 | Server: Hey client, please stop doing NAWS |
Handshake plus initial message
Height and Width are 16 bit values, requiring 2 octets each. Any occurrence of a value of 255 must be doubled