Remote XDMCP connection ending every two hours

[rwbenton]

I am going through cygwin's XWin.exe (XWin - queary <hostname>) to start a remote session with a RHEL 5.5 workstation. I have run gdmsetup on the worksation to allow the remote connection. Starting the remote session goes off without a problem.

After about two hours, it just exits and I have to start over. This is a problem since all my gui's are killed and I have some important processes running.

/var/log/syslog/messages shows:

Jun 15 16:49:53 <host> gconfd (root-12016): SIGHUP received, reloading all databases
Jun 15 16:49:53 <host> gconfd (root-12016): Resolved address "xml:readonly:/etc/gconf/gconf.xml.mandatory" to a read-only configuration source at position 0
Jun 15 16:49:53 <host> gconfd (root-12016): Resolved address "xml:readwrite:/root/.gconf" to a writable configuration source at position 1
Jun 15 16:49:53 <host> gconfd (root-12016): Resolved address "xml:readonly:/etc/gconf/gconf.xml.defaults" to a read-only configuration source at position 2
Jun 15 16:49:53 <host> gconfd (root-12016): GConf server is not in use, shutting down.
Jun 15 16:49:53 <host> gconfd (root-12016): Exiting
Jun 15 16:50:02 <host> gconfd (rjleahy-11753): GConf server is not in use, shutting down.
Jun 15 16:50:02 <host> gconfd (rjleahy-11753): Exiting

There must be a 2 hour timeout set somewhere - maybe in a gconf xml file?

Thanks for any input to nail this down, it is driving me and my team crazy.

[HROAdmin26]

I have seen this type of timeout be a firewall setting in many cases - IE. there is a hard timeout on TCP sessions and then the session is cut. In one example, a backup always failed after running for 1 hour.

[rwbenton]

Thanks for the suggestion. The network team responded that they do have protocol timeouts set for 30 minutes but there must be a keep-alive process that is extending the session for 2 hours prior to shutting down the port.

They are looking into the problem and will get back to me. I'll update once they have a solution.

[wildpossum]

If your doing so via a SSH connection: You can send keep alive signals if ssh daemon is setup to expect one. on your host (from where you ssh into device) you can add

ServerAliveInterval 60

to ~/.ssh/config

this will send a no-op every minute and your session will remain alive.

[jippie]

SSH is by far a better option than using XDMCP. XDMCP is by design insecure as anyone can set up a connection to a server and the traffic across the network is uncompressed and in 'clear text'.
If you are in the position to change to X11 over SSH, I'd do that asap. from a security standpoint.
Also, as wildpossum stated above, SSH is easily configurable to keep sessions alive and alse only needs a single TCP port opened in the firewall(s).

Hope this helps.

[rwbenton]

Thanks for all the help.

I have Cygwin-X installed and I bring up the X-Win Server shell then type:

ssh -X -v <hostname>

At that point I'm able to launch any gui's from the shell. I can even launch gnome-session or startkde (thanks to Van Emery's page).

I would like to run it in a fixed single window that doesn't automatically take up my entire two screens. I will keep playing with it.

Thanks again.

[jippie]

you should check out Xming, it is on sourceforge.net and is based on Cygwin. The good thing about Xming is a graphical wrapper to help you with exactly the problem you describe, wether you want the root window (id 0) in a Windows-window or no.

[rwbenton]

Found a page using xinit on Roy's Musings. Here are the steps:

1) Bring up a Cygwin shell and type:

xinit -- -clipboard

2) A new shell and Xwindow (windowed) are opened taking up only one screen. From the new shell type:

ssh -l <username> -X -v <host or IP>

3) This opens the ssh session (with X tunneling). I then typed:

gnome-session

The remote gnome session opened. Our firewall already keeps ssh sessions alive so no more timeout issues.

The neat thing is, I can copy clipboard items from the gnome desktop to my windows desktop.

Thanks for all the help everyone.