There are a LOT of good sites out there for Unix security in general
and Linux security specifically. It's very important to subscribe to one
(or more) of the security mailing lists and keep current on security
fixes. Most of these lists are very low volume, and very
informative.
The LinuxSecurity.com web site has numerous Linux and open source
security references written by the LinuxSecurity staff and people
collectively around the world.
Linux
Advisory Watch -- A comprehensive newsletter
that outlines the security vulnerabilities that have been
announced throughout the week. It includes pointers to updated
packages and descriptions of each vulnerability.
Linux Security
Week -- The purpose of this document is to
provide our readers with a quick summary of each week's most
relevant Linux security headlines.
The COAST archive has a large number of Unix security
programs and information: COAST
CERT, the Computer Emergency Response Team, puts out
advisories on common attacks on Unix platforms: CERT home
Dan Farmer is the author of SATAN and many other security
tools. His home site has some interesting security survey
information, as well as security tools: http://www.trouble.org
