X server issues fixed

Display problems and a potential vulnerability related to our remote access system have been fixed.

The problem:

  1. We enabled all users to run X servers remotely (in /etc/X11/XWrapper.config).
  2. Remote X session run through Xdummy locked the primary display.
  3. Changes in the user-level xorg.conf caused rendering problems on the lab display.
  4. If the remote user executed startx to directly initialize an X session (no dummy display), this session supplanted the root session on the lab display. Yikes!

The solution:

  • Disabled remote execution of X server
  • Remote display access and display sharing are now through x2go.

A side-effect of this is that the KDE desktop environment is now available on hilley-agisoft-linux. (This is used by x2go.)