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 a server oriented Os intend to high security level
users. With is own great fire-walling tool,
pf as a very reliable Os
gateway. It is also great for running untrusted programs like user
cgis in a web server. It contains stack protection features that
make the gain of privileges using buffer overflows very difficult.