This page intends to allow remote sessions using "X Display Manager Control Protocol" (XDMCP). See the GDM documention for more information on the parameters: http://library.gnome.org/admin/gdm/3.6/configuration.html.en#xdmcpsection.
- 1 Setup Graphical Logins
- 2 Accessing X from a remote Machine on your LAN
- 3 Thin client setup
- 4 Troubleshooting
Setup Graphical Logins
/etc/X11/xdm/xdm-config and comment out:
So it will be:
/etc/X11/xdm/Xaccess to allow any host to get
a login window. Look for a line that looks like this:
* #any host can get a login window
and remove the hash '#' sign at the beginning of the line.
In case you have multiple network interfaces also add a line like this:
Where 192.168.0.10 should be you server IP address.
Then reboot or restart your X server and xdm daemon.
/etc/gdm/custom.conf to include:
[xdmcp] Enable=true Port=177
Then restart the Gnome Display Manager:
systemctl restart gdm
Or if using the inittab method, login as root on another tty and
telinit 3 telinit 5 && exit
Support for this feature seems to be very buggy. Lightdm is probably an easier choice.
Edit 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:
systemctl restart kdm
SLiM doesn't support Xdmcp.
Accessing X from a remote Machine on your LAN
You can access your login manager on the network computer 192.168.0.10 via the following command. TCP and UDP streams are opened. So it is not possible to access the login manager via an SSH connection.
Xnest -query 192.168.0.10 -geometry 1280x1024 :1
Or, with Xephyr, if you experience refreshing problems with Xnest:
Xephyr -query 192.168.0.10 -screen 1280x1024 -br -reset -terminate :1
Or, if you are on runlevel 3
X -query your_server_ip
Xserver should recognize your monitor and set appropriate resolution.
After allowing XDMCP access as described above, edit
/etc/X11/xdm/Xservers and comment out:
#:0 local /usr/bin/X :0
Then launch XDM as root, e.g.
xdm -config /etc/X11/xdm/archlinux/xdm-config
Thin client setup
XDMCP fatal error: Manager unwilling Host unwilling
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 asterisk '
*'. 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.
Session declined: Maximum Number of Sessions Reached
/etc/gdm/custom.conf and add/increase the maximum sessions.
[xdmcp] Enable=true MaxSessions=2
If you still cannot log in remotely
...and you see only a black screen, try removing the
-nodaemon option in
/etc/inittab to have only
Login screen and GNOME is somehow flickering
If the login screen is created again and again and unresponsive, you are trying to access GNOME Shell on the remote machine. This is apparently caused by network speed, e.g. by accessing via wireless connections. The workaround is to disable/deinstall GNOME Shell.
pacman -R gnome-shell