FreeBSD 8.1 Final

FreeBSD® is an advanced operating system for x86 compatible (including Pentium® and Athlon™), amd64 compatible (including Opteron™, Athlon™64, and EM64T), UltraSPARC®, IA-64, PC-98 and ARM architectures. It is derived from BSD, the version of UNIX® developed at the University of California, Berkeley. It is developed and maintained by a large team of individuals. Additional platforms are in various stages of development. The FreeBSD developers are as concerned about security as they are about performance and stability. FreeBSD includes kernel support for stateful IP firewalling, as well as other services, such as IP proxy gateways, access control lists, mandatory access control, jail-based virtual hosting, and cryptographically protected storage. These features can be used to support highly secure hosting of mutually untrusting customers or consumers, the strong partitioning of network segments, and the construction of secure pipelines for information scrubbing and information flow control.

FreeBSD also includes support for encryption software, secure shells, Kerberos authentication, "virtual servers" created using jails, chroot-ing services to restrict application access to the file system, Secure RPC facilities, and access lists for services that support TCP wrappers.
Link : FreeBSD 8.1 Final For i386 http://adf.ly/7CAB
Link : FreeBSD 8.1 Final For amd64 http://adf.ly/7CAD
Link : FreeBSD 8.1 Final For ia64 http://adf.ly/7CAH