[Beowulf] security for small, personal clusters

[Mark Kosmowski]

What kind of security is recommended for the owner of a small personal
cluster?  Where should the owner of a small, personal cluster go to
learn about security?  Doing searches tends to give a few "head in the
sand" sites but predominantly seem to be oriented for the security
professional.

I maintain a small 3 node personal cluster used for my part-time PhD
studies in chemistry.  So far I've just kind of been hoping that I'm
too small to bother with and that the firewalls (Linux and switch)
between my boxes and the cable internet do something.  I do use ssh
for cluster communications, and have disabled the reknowned unstable
services such as ftp.

RGB mentioned running services on non-standard ports.  This seems like
a good idea to further reduce the probability of successful attack.
I'll look into this in a couple weeks when I'm laid off and will have
more time on the IT side of things.

Are there any good sites aimed at the small user to slowly learn a
little bit about security?  Or are the only choices to do security
full-time or forget about it entirely?

What sorts of security do other here have on their personal clusters?
Is maybe the simplest idea to just disable TCP/IP across the internet
network while not in use and enable it when it needs to be up?

Thanks,

Mark E. Kosmowski