[plug] vnc - strange behaviour under Centos

[Peter Sutter]

On Wednesday 08 July 2009 10:31, Denis Brown wrote:
> At 10:17 AM 4/07/2009, you wrote:
> >Vncserver is started up via xinetd on a CentOS 5.3 host, either virtual or
> >real. I can connect to the server via vnc and get the login screen. I can
> >also login as either a user or as root and get the corresponding desktop.
> >
> >What happens next is CentOS 5.3 specific, as it works well on SuSE Linux,
> >Ubuntu etc. On a CentOS 5.3 host, when I am connected as a normal user via
> >VNC,  and I try to open a 'privileged' program (one that would prompt for
> > a root password) or anything else that requires the root password,
> > neither the password dialog nor the program will show up.
> >
> >Trying the same but logged in as root, the program will just not display.
> > No errors in any of the logs.
> >
> >Anybody having the same problems? How did you fix it?
>
> Hello Peter,
>
> This could be way off track but recent experience with Centos suggests that
> turning off (temporarily?) SElinux may help.
>
> I have had some installations go pear-shaped unless SElinux was disabled.
>
> HTH,
> Denis
>
No, the problem is that it can not properly find the X server.

Running the program in an xterm produces 

[sutterp at vaire ~]$ pirut
Xlib: connection to "localhost.localdomain:2.0" refused by server
Xlib: No protocol specified

Unable to import modules. Maybe you're not running under X?

echo $DISPLAY in the xterm gives localhost.localdomain:n.0,

setting export DISPLAY=:n.0 will make the program work out of xterm.

I could not yet figure out whether this is due to a mis-configuration or a 
bug. Either vncviewer or gnome gets it wrong when running under vnc, as it 
runs ok under X.

Peter