Allowing Remote X Sessions
Under Mandrake

Edit the file

/usr/share/config/kdm/kdmrc

Enable the Xdmcp by making the following edit:

[Xdmcp]
Enable=true
KeyFile=/etc/X11/xdm/xdm-keys
Willing=
Xaccess=/etc/X11/xdm/Xaccess

Now restart your X server.