I will look here at Red Hat 8.0. I have found very little information for starting X using gdmchooser. The man page is pretty much non existant; so I thought I would write a sort of Howto :-)


The file to edit is /etc/X11/gdm/gdm.conf


You should run gdmconfig (in X) or edit the gdmconfig file to enable XDMCP. Please filewall XDMCP at your network boundary for security.


The following changes need to be made:


enable XDMCP by setting to true (I have increased displays per host from 1 to 5 as I sometimes run a couple of Xnests):

 [xdmcp]
 # Distributions: Ship with this off. It is never a safe thing to leave
 # out on the net. Alternatively you can set up /etc/hosts.allow and
 # /etc/hosts.deny to only allow say local access.
 Enable=true
 HonorIndirect=true
 MaxPending=4
 MaxPendingIndirect=4
 MaxSessions=16
 MaxWait=15
 MaxWaitIndirect=15
 DisplaysPerHost=5
 Port=177
 

I then changed the servers configuration towards the bottom of the file. Please note that desktop.harkness.co.uk is my desktop machine that X is running on locally. Change this to the machine name that you are editing.

 [servers]
 #0=Standard
 #0=Chooser
 #1=Standard
 #Note: If you want to make sure X runs on a specific virtual console on linux,
 # you can use the following (for console 7). However this can cause
 # problems for some users. Be careful about this, getting this wrong
 # can lead to an unusable console. Best solution is to make sure gdm
 # starts as the last thing, and that will make it not neccessary to
 # do hacks like this.
 #0=Standard vt7
 #
 #Note: If you want to run an X terminal you could add an X server such as this
 #1=Terminal -query sunbox.harkness.co.uk
 0=Terminal -indirect desktop.harkness.co.uk
 # or for a chooser (optionally serverhostname could be localhost)
 #0=Terminal -indirect serverhostname


Then restart gdm or go from init level 3 to 5 and you should be presented with a chooser. Note that this did not happen the first time I tried as I had a couple of zombie gdm processes.


All is now left is to enable XDMCP on all the other machines that you want to run.