Network Working Group G. Marcy Request for Comments: 1096 Carnegie Mellon University March 1989 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 , 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.
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:
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  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