[CentOS] How to setup VNC for GDM access on 6.3

Wed Jan 23 10:48:32 UTC 2013
Ron Yorston <rmy at tigress.co.uk>

Bruce Ferrell wrote:
>I'm looking for pointer for setting up VNC so that access to the system
>is via gdm/kdm.  Yes, I know about vino, and /etc/sysconfig/vncservers
>but what I'm looking for is a sertup that allows me to see the *dm login
>screen instead of being dropped direct into a desktop.

I set this kind of thing up many years ago on CentOS 4.  I was curious to
see if it still worked on CentOS 6 and found that this works for me:

   Edit /etc/gdm/custom.conf to add 'Enable=true' to the '[xdmcp]'
   section.  Restart gdm.  (I just did 'telinit 3; telinit 5'.)

   Run this command to start a server:

   /usr/bin/Xvnc :1 -query localhost -geometry 1100x850 -securitytypes none &

Given a properly configured (or disabled) firewall you should then be able
to run 'vncviewer hostname:1' to get a login screen.

Once you've logged in the session will persist even if you close vncviewer,
so you can reconnect later.  This is, of course, hopelessly insecure.

Starting Xvnc from xinetd is also possible, but then sessions aren't

For some reason that I've never been able to fathom if you log out from
a persistent session there's an annoying delay until the login screen