I was poking around the xdm man page (under Irix 5.3) and found the following note, which I hadn't heard very much of before: 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). I checked a few machines here, and sure enough, if you can log onto the machine, you can disable their xauthority and open the display. Looking back at a 5.2 machine, it would appear to work fine there also. Now, its nice to document it in the man page, but I've not heard this mentioned before, so I thought I would pass it along.. Paul Danckaert, Systems