grsecurity is a complete security system for Linux
2.4 and 2.6 that implements a
detection/prevention/containment strategy. It
prevents most forms of address space modification,
confines programs via its Role-Based Access
Control system, hardens syscalls, provides
full-featured auditing, and implements many of the
OpenBSD randomness features. It was written for
performance, ease-of-use, and security. The RBAC
system has an intelligent learning mode that can
generate least privilege policies for the entire
system with no configuration. All of grsecurity
supports a feature that logs the IP of the
attacker that causes an alert or audit.