ssh_config's Hosts directive

[Andrew Stribblehill]

I'm trying to arrange the SSH client here to default to allowing
X forwarding etc. to local machines (within the .dur.ac.uk domain)
without forwarding X to off-site machines.

Now, I read that the hostname isn't canonicalised (what a horrible
word!) so I presume I have to match on both *.dur.ac.uk and
*-without-any-dots-in-it. How do I do this in practice?

If ssh is presently not configurable enough to do this, can we
extend the functionality of Hosts in some useful but still
backward-compatible manner?

Thanks,

Andrew Stribblehill
Systems programmer, IT Service, University of Durham