Mailing the story:

Is your server as secure as it could be? Sure, you use a firewall, mandate strong passwords, and patch regularly. You even take a proactive approach by performing security audits with tools such as nmap and Nessus. Yet you may still be vulnerable to zero-day exploits and privilege escalation attacks. If these possibilities keep you awake at night, you're not alone. The sleepless folks with the grsecurity project have developed an easy-to-use set of security enhancements to help put your fears to rest.