T8
After some experimentation, this seems to be the case regarding remote 
logins to a leopard (machine in the lab).

The machine needs to be awake for you to ssh into it. So if your favorite
leopard is asleep, log into another one. Currently, beltrami, descartes and
a few others are forced to stay awake.

Once you're logged you need to mont dent in /Volumes. So open a shell and
$cd /Volumes
$ls
If you notice that there is a netgroups already there, you probably cannot
cd into it from a remote login. That's what I discovered this evening. 
Instead, however, you can create a new mount point thus. Suppose you're ivanhoe.
$mkdir ivanhoedent
$mount_afp -i afp://dent.math.uiuc.edu/netgroups /Volumes/ivanhoedent
authenticate yourself, and presto, you now can get into dent.

This is NOT the way the world is supposed to be, but for now, that's it.

Ohhh, and to be polite, when you're done you should 
$umount /Volumes/ivanhoedent
which removes your personal mount point instead of leaving it lying around
as a permanent monument to your visit to /Volumes.