> I believe the protocol used is XDMCP, and works as follows:
>
> Client sends a udp packet to the subnet broadcast address, on port 177, and
> all the servers on the local subnet respond.
That's when the XDMCP client (X display) is looking for any
XDMCP server that will display a window and offer services
to the user. This service *may* be a menu service to select
to which machine the user actually wished to log in.
Many XDMCP clients also have an option of selecting a
specific machine from a local menu and sending a directed
XDMCP packet to that machine.
> I have no idea why this would ever work through a router, unless the router is
> forwarding network broadcasts (which is generally a bad thing).
I'd agree in the first case. In the second case it *should*
work through a router. A straightforward UDP "keep state"
rule shoudl allow the XDMCP packets through. Once the XDMCP
negotiation(s) are complete, the server will need to display
a login window on the client which is a X11 call from the
server to port 6000 on the client.
--
David Pick
