The process of securing a system against external threats; to make more difficult to penetrate. Taken from the real-world term as to "firing" clay to make pottery or manufacturing stronger metal alloys.
A term for a user taking countermeasures to avoid being infected with malicious code by Bad Guys such as applying a hardware or software firewall, configuring or disabling services running on the system, and anti-virus (for Windows) among others.
- Hardening HOWTOs
- OpenWall - OpenWall (aka OW) Linux kernel patch by Solar Designer. This was the first Linux kernel patch which provided hardening.
- HAP-Linux patch - Hank Approved Paranoid Linux. A patch to be applied after OW. Provides some additional features like chroot hardening and ptrace protection.
- GrSecurity - A complete security patch for Linux with many features
- PaX - Documentation and source from the PaX team (PaX is a part of GrSecurity).
- Stephanie - Patch for OpenBSD. Patches kernel, manpages and a few other programs like sysctl. Many 'hardening' features like random PID's and W^X are already in OpenBSD by default.
- Papillon - Solaris 8/9 security module. Code inspired by OpenWall.