“This IPv4-centric document is meant both as an overview to the IP Security Protocol (IPsec) and as an introduction to OpenBSD’s implementation of it. By the end the reader will have learned how to set up various types of IPsec installations on OpenBSD. Each type of installation includes guidance regarding firewall protection using, of course, the unsurpassed OpenBSD packet filter.”
OpenBSD simply rocks for anything network. Stable as a rock, secure and simple as hell to configure. And, as opposed to anything in the Linux camp, stuff is documented.