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Revision as of 12:45, 15 May 2010 by Sandstorm (talk | contribs) (Added command to access login manager via network)
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This page intends to allow remote sessions using "X Display Manager Control Protocol" (XDMCP).


One way to start the X server is through kdm, and if you want to be able to login remotely to your kde session from a remote machine, you need to allow xdmcp. To do this edit your kdmrc ( /opt/kde/share/config/kdm/kdmrc [KDE 3x] or /usr/share/config/kdm/kdmrc (KDE 4x] ) and at the end there should be something like this:


Then you need to restart your X server so the change you just made takes effect:

/etc/rc.d/kdm restart


If you prefer to use GDM instead of KDM, the manipulation is basically the same. Edit /etc/gdm/custom.conf according to the following snippet:


The restart the Gnome Display Manager:

/etc/rc.d/gdm restart

It is even possible to do all this using the graphical GDM configuration tool (gdmsetup) from a local X session or through the network using ssh -X.

Now you should be able to login remotely using your prefered session/WM. Enjoy!


SLiM doesn't support Xdmcp.

Accessing X via network

You can access your login manager on the network computer via the following command. TCP and UDP streams are opened. So it is not possible to access the login manager via an SSH connection.

X -query :1


XDMCP fatal error: Manager unwilling Host unwilling

When connecting to the X server from a remote host you get:

Fatal server error:
XDMCP fatal error: Manager unwilling Host unwilling

Your current settings are too restrictive. Edit /etc/hosts.allow to allow remote connexions to display manager. Add this line if you use GDM:

 gdm: ALL


This is usually caused by an entry missing from the "/etc/kde3/kdm/Xaccess" file. This file controls which machines can connect to the server via KDM. The trick is to add a line that starts with an Aster- isk '*'. Look for a line that looks like:

      # *                                     #any host can get a login window

and remove the hash '#' sign at the beginning of the line. Then, you need to restart KDM.

/etc/rc.d/kdm restart

Test in Ubuntu Server 8.04. Source: http://www.bogor.net/idkf/idkf-wireless/aplikasi/linux/low-cost-thinclient/lts_tsguide_v2.2.txt

Session declined: Maximum Number of Sessions Reached

Edit /etc/gdm/custom.conf and add/increase the maximum sessions.