Here is a link to another article about securing one's Linux box.
Thanks for the linkage. I have to disagree with some points in the article though.
Nmap is used by more than just crackers, it used by hackers and sysops to secure their network. I use Nmap to scan my network for problems and nesses addons for an easy assesment and charted format of posible problems. Saying that Nmap is used by 'hackers' to create a map of your network is like saying traceroute is a 'hacker' tool used to find and destroy your system on the internet.Nmap is a program used by hackers to create a map of your network. It is often the first step a hacker takes once he or she has access to your network to determine which system to hack. Nmap lists the systems and the services on the network.
Which would probably be Nessus+nmapAdministrators must also regularly test their systems using security analyzer software. Security analyzer software scans systems to uncover security vulnerabilities, and recommends fixes to close the security hole.
The article doesn't mention layering. In security you generally want to have layer after layer as failsafe and for log sifting just in case. While the article promotes layering without stating it layering is an esential part of host security.
Some other invaluable tools in the hackers ('Administrators' protection toolset are: Portsentry and Logsentry (Now owned and discontinued by Cisco), Snort IDS, Linux Netfilter, grsecurity, and LIDS.