Practical Unix & Internet Security (2nd ed.)
Garfinkel and Spafford
and to read it through. It is not a small book, and it does tend to make
one a trifle paranoid, but that is probably an appropriate state of mind
these days. There are web sites with more detailed information, as well as
lists with up-to-the-minute security information, but just becoming
security-conscious is probably the most important thing.
The suggestions about disabling routed (almost never needed in normal
situations) and not having a default route are very good ones, too, if you
really do not need for particular machines to be accessible. Also, don't
run any services that you don't actually need. The default configuration
for most workstations assumes you want to provide all kinds of services that
you probably have no use for, or for which there are more secure
substitutes. That is less of a problem if the routing is set up so that
your machine won't talk to anything outside your local net.
-- Steve Philson philson@nmr.chem.umn.edu Director NMR Lab 612-626-0297 Chemistry Dept. University of Minnesota