I just installed a test machine with Ubuntu LTS 14.04 and I went to configure the XDMCP access and found that the file
/etc/lightdm/lightdm.conf is not there anymore.
In Google I found that now it is in
/usr/share/lightdm/lightdm.conf.d/50-ubuntu.conf and there I modified the settings to enable XDMCP and some others:
[SeatDefaults] user-session=ubuntu greeter-show-manual-login=true [XDMCPServer] enabled=true [SeatDefaults] xserver-allow-tcp=true
But when I try to log in using Xming from a windows machine, I can enter the username and password but afterwards no desktop appears, only the background from the login screen.