can't open display...
 

Hi folks,
I read through some of the posts and haven't been able to fix the "can't open display problem. Running a re-installed rhel5.2 linux version. Can't open a display when 'ssh -X <sgi machine>' or 'ssh -Y <sgi machine>'
'xhost +' enabled on rhel5.2, DISPLAY set on client, /etc/ssh/ssh_config has X11TrustedForwarding set to 'yes'. Not sure what else to try.
Thanks.

What specifically are you doing? Can you walk us through it?

Just wondering, are both these machines red hat boxes? It sounds like you might have the config files correct, but yes please provide a little bit more information on the exact problem and the OSs involved.

Some clarification: I have a linux box on my desk running RHEL 5.2. I 'ssh -Y <SGI box ip address>'. So on the linux box I have 'xhost +' enabled. I run a secure shell to an SGI box. I am able to connect and immediately set my display using the tch, 'setenv DISPLAY <ip_address of my linux box:0>' I get the can't open display message. This is some sort of configuration or xauth issue. I already set 'X11Forwarding' to yes and 'X11TrustedForwarding' to yes in /etc/ssh/ssh_config' to yes even though I don't have to when using 'ssh -Y' from the command line. I copied the xauth from my linux box to the remote SGI box using the command 'xauth extract - $DISPLAY | rsh <remote machine> xauth merge -'. I still get the can't open display for just trying to open an xterm. This used to work. RHEL 5.2 was re-installed on my linux box after faulty hard drive removed and a new one was installed. There must be something I need to set up on the SGI remote side, since I can open an xterm when connecting to another linux box running RHEL 5.2.

On your desktop, are you running gdm?
If so, is it set to deny tcp access to the xserver? (by default it is)
Also, is it possible a firewall may be blocking access to you x server?

Hi,

From what i have worked the configuration steps are:

On the remote box:
- Enable X11Forwarding on /etc/ssh/sshd_config
- Be sure to restart the sshd daemon to the new configuration is applied.
- The firewall on the SGI box has to allow connections via local interface
(haven't seen an SGI box en years so i don't remember the interface names)
so check your firewall rules also.
- The box needs an xauth command in the path so the ssh service can
negotiate the X authentication.

On the client, enable X11 on the /etc/ssh/ssh_config (not sshd_config)
o start the connection with
ssh -X user@remotebox

When logged, the DISPLAY variable on the remote machine should be
automatically set to localhost:10.0 (could be 11:0,12.0 etc. if other
people is logged), there is no need to set the DISPLAY variable or
use the xhost command, when using ssh+x11 forwarding,
all traffic is sent through the ssh tunnel.

In order to debug, you have to check:
- Locally, from the same terminal you should be able to
start a new X app (xeyes, xterm etc.), you local
DISPLAY variable should be ok if you can do that.
- After login to the remote box the DISPLAY variable
should be localhost:10.0 or similar, that confirms that
sshd is setting up the X11 forwarding.
- If the DISPLAY variable is set correctly but you still
can't start applications check your firewall.

Best regards,