/etc/sysconfig/displaymanager

Edit – DISPLAYMANAGER_REMOTE_ACCESS=”yes”

/etc/opt/kde3/share/config/kdm/kdmrc
/etc/opt/kde3/share/config/kdm/kdmrc.SuSEconfig

Set true here:

[Xdmcp]
Enable=true
Willing=/etc/X11/xdm/Xwilling
Xaccess=/etc/X11/xdm/Xaccess

then
/etc/X11/xdm

Edit: Xaccess

Cheack that you have * for all host

and in xdm-config

Set this:

DisplayManager.requestPort: 177

Restart the X Server