The "Nessus" Project was started by Renaud Deraison in 1998. This is a patch auditing tool for UNIX and Windows hosts without the need for an agent.
I am using this program for a long time for a great accuracy of the patch auditing. Once of my the must have tool.
Personal use - Free.
Nice pentesting program
Such a great program for the Vulnerability check. I'm using this for a long time.