Browse Prior Art Database

Telnet window size option (RFC1073) Disclosure Number: IPCOM000001882D
Original Publication Date: 1988-Oct-01
Included in the Prior Art Database: 2000-Sep-12
Document File: 4 page(s) / 7K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

D. Waitzman: AUTHOR


Status of this Memo

This text was extracted from a ASCII document.
This is the abbreviated version, containing approximately 40% of the total text.

Network Working Group D. Waitzman

Request For Comments: 1073 BBN STC

October 1988

Telnet Window Size Option

Status of this Memo

This RFC describes a proposed Telnet option to allow a client to

convey window size to a Telnet server. Distribution of this memo is


1. Command Name and Option Code

Name = NAWS (Negotiate About Window Size)

Code = 31

2. Command Meanings


Sent by the Telnet client to suggest that NAWS be used.


Sent by the Telnet client to refuse to use NAWS.


Sent by the Telnet server to suggest that NAWS be used.


Sent by the Telnet server to refuse to use NAWS.

IAC SB NAWS <16-bit value> <16-bit value> IAC SE

Sent by the Telnet client to inform the Telnet server of the

window width and height.

The window size information is conveyed via this option from the

Telnet client to the Telnet server. The information is advisory.

The server may accept the option, but not use the information that is


The client and server negotiate sending the window size information

using the standard Telnet WILL/DO/DON'T/WON'T mechanism. If the

client and server agree, the client may then send a subnegotiation to

convey the window size. If the client's window size is later changed

(for instance, the window size is altered by the user), the client

may again send the subnegotiation. Because certain operating

systems, on which a server may be executing, may not allow the window

size information to be updated, the server may send a DON'T NAWS to

the client to forbid further subnegotiation after it was initially

accepted. A negotiation loop will not form following these rules.

The subnegotiation consists of two values, the width and the height

of the window in characters. The values are each sent as two bytes,

in the Internet standard byte and bit order. This allows a maximum

window width or height of 65535 characters. A value equal to zero is

acceptable for the width (or height), and means that no character

width (or height) is being sent. In this case, the width (or height)

that will be assumed by the Telnet server is operating system

specific (it will probably be based upon the terminal type

information that may have been sent using the TERMINAL TYPE Telnet


The syntax for the subnegotiation is: