Telnet X Display Location Option

Status of This Memo

This RFC specifies a standard for the Internet community. Hosts on the Internet that transmit the X display location within the Telnet protocol are expected to adopt and implement this standard. Distribution of this memo is unlimited.

This standard is modelled on RFC 1079 [1], the telnet terminal speed option. Much of the text of this document is copied from that RFC.

Motivation

When a user is running the Telnet client under the X window system, it is useful for the remote Telnet to know the X display location of that client. For example, the user might wish to start other X applications from the remote host using the same display location as the Telnet client. The purpose of this option is to make this information available through telnet connections.

1 Command Name and Code

X-DISPLAY-LOCATION (XDISPLOC)

      Code = 35

2 Command Meanings

IAC WILL X-DISPLAY-LOCATION

Sender is willing to send the X display location in a subsequent sub-negotiation.

IAC WON'T X-DISPLAY-LOCATION

Sender refuses to send the X display location.

IAC DO X-DISPLAY-LOCATION

Sender is willing to receive the X display location in a subsequent sub-negotiation.

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IAC DON'T X-DISPLAY-LOCATION

Sender refuses to accept the X display location.

IAC SB X-DISPLAY-LOCATION SEND IAC SE

Sender requests receiver to transmit his (the receiver's) X display location. The code for SEND is 1. (See below.)

IAC SB X-DISPLAY-LOCATION IS ... IAC SE

Sender is stating his X display location. The code for IS is 0. (See below.)

3 Default

WON'T X-DISPLAY-LOCATION

The X display location will not be exchanged.

DON'T X-DISPLAY-LOCATION

The X display location will not be exchanged.

4 Description of the Option

WILL and DO are used only to obtain and grant permission for future discussion. The actual exchange of status information occurs within option subcommands (IAC SB X-DISPLAY-LOCATION...).

Once the two hosts have exchanged a WILL and a DO, the sender of the DO X-DISPLAY-LOCATION is free to request the X display location. Only the sender of the DO may send requests (IAC SB X-DISPLAY- LOCATION SEND IAC SE) and only the sender of the WILL may transmit actual X display location (within an IAC SB X-DISPLAY-LOCATION IS ... IAC SE command). The X display location may not be sent
spontaneously, but only in response to a request.

The X display location is an NVT ASCII string. This string follows the normal Unix convention used for the DISPLAY environment variable, e.g.,

         <host>:<dispnum>[.<screennum>]

No extraneous characters such as spaces may be included.

The following is an example of use of the option:

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Host1: IAC DO X-DISPLAY-LOCATION

Host2: IAC WILL X-DISPLAY-LOCATION

(Host1 is now free to request status information at any time.)

Host1: IAC SB X-DISPLAY-LOCATION SEND IAC SE

Host2: IAC SB X-DISPLAY-LOCATION IS "SRI-NIC.ARPA:0.0" IAC SE

(This command is 22 octets.)

5 Implementation Suggestions

Since the X display location may not contain a hostname on the client host, i.e., ":0" or "unix:0.0", the Telnet client will need to modify the location appropriately before sending it on to the remote Telnet.

Reference

[1] Hedrick, C., "Telnet Terminal Speed Option", RFC 1079, Rutgers University, December, 1988.

Author's Address:

Glenn A. Marcy
Carnegie Mellon University
School of Computer Science
Pittsburgh, PA 15213-3890

Phone: (412) 268-7669

Email: Glenn.Marcy@CS.CMU.EDU

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