LinuxSecurity.com: Hacks From Pax: Network Server Monitoring With Nmap

“Today we’ll discuss hardening Linux servers by scanning for
unnecessarily open network ports, and we’ll show you how to
automate port scanning so you can easily monitor your network for
vulnerabilities.

“Portscanning, for the uninitiated, involves sending connection
requests to a remote host to determine what ports are open for
connections and possibly what services they are exporting.
Portscanning is the first step a hacker will take when attempting
to penetrate your system, so you should be preemptively scanning
your own servers and networks to discover vulnerabilities before
someone unfriendly gets there first…”

Complete
Story