- The X Display Manager Control Protocol (XDMCP) uses UDP port 177. An X server requests that a display manager start a session by sending a Query packet. If the display manager allows access for that X server, it responds by sending a Willing packet back to the X server.
This allows for opening X sessions remotely.
Setup graphical logins
Comment the last line of the configuration file with a
Then allow any host to get a login window in by un-commenting the following:
* #any host can get a login window
In case you have multiple network interfaces also add a line like this:
192.168.0.10 is your server IP address.
Enable XDMCP in the configuration file:
[xdmcp] Enable=true Port=177
Enable the XDMCP Server in the configuration file:
[XDMCPServer] enabled=true port=177
On a headless system, disable the automatic start of one seat so that LightDM can run in the background:
Accessing X from a remote machine on your LAN
You can access your login manager on the network computer (using
192.168.0.10 in 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 server address
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
- Xming for Windows
Session declined: Maximum Number of Sessions Reached
/etc/gdm/custom.conf and increase
[xdmcp] Enable=true MaxSessions=X