”Only one remote hole in the default install, in more than 8 years!
The OpenBSD project produces a FREE, multi-platform 4.4BSD-based UNIX-like operating system. Our efforts emphasize portability, standardization, correctness, proactive security and integrated cryptography. OpenBSD supports binary emulation of most programs from SVR4 (Solaris), FreeBSD, Linux, BSD/OS, SunOS and HP-UX.”
OpenBSD is probably the most secure operating system there is. Perfect for firewalls and similar things.