DisplayManager.DISPLAY.authorize

DisplayManager.DISPLAY.authName

     authorize is a boolean resource which controls whether xdm
     generates and uses authorization for the local server
     connections.  If authorization is used, authName is a
     whitespace-separated list of authorization mechanisms to use.
     XDMCP connections dynamically specify which authorization
     mechanisms are supported, so authName is ignored in this case.
     When authorize is set for a display and authorization is not
     available, the user is informed by having a different message
     displayed in the login widget.  By default, authorize is
     ``true''; authName is ``MIT-MAGIC-COOKIE-1.''  Warning for SGI
     installations: With X authorization on, clients can still connect
     to the display using shm:0, even if they are not "authorized" to
     do so. As a workaround for this bug, you can disable the use of
     the shared memory transport, by adding the -shmnumclients 0
     option to the X invocation in /usr/lib/X11/xdm/Xservers (see the
     Xsgi man page).