For any Linux distro, applying the grsecurity patchset will make your box more secure.<p>RHEL (and thus, CentOS) does a pretty good job of configuring and enabling SELinux for packaged software.<p>There is a Hardened Gentoo. All the fun of normal Gentoo, but with fewer companions to find the compiler bugs. ;-) Still, they&#x27;ve built quite a stack of security patches, including grsecurity.<p>There is (used to be?) Hardened Linux From Scratch. Educational, but not practical.<p>OpenWall Linux is dead-ish, but - as you&#x27;d expect from a Solar Designer product - introduced several interesting patches (some backported from OpenBSD). You may be interested in <a href="http:&#x2F;&#x2F;www.openwall.com&#x2F;presentations&#x2F;Owl&#x2F;" rel="nofollow">http:&#x2F;&#x2F;www.openwall.com&#x2F;presentations&#x2F;Owl&#x2F;</a>.<p>I recommend - and use - OpenBSD, but there are definitely people interested in security in the Linux world.