OpenBSM is an open source implementation of Sun's Basic Security Module (BSM)
Audit API and file format. BSM, the de facto industry standard for Audit,
describes a set of system call and library interfaces for managing audit
records, as well as a token stream file format that permits extensible and
generalized audit trail processing. OpenBSM extends the BSM API and file
format in a number of ways to support features present in the Mac OS X and
FreeBSD operating systems, such as Mach task interfaces, sendfile(), and
Linux system calls present in the FreeBSD Linux emulation layer.

WWW: http://www.trustedbsd.org/openbsm.html