audit(4) Security Event Audit


options AUDIT


Security Event Audit is a facility to provide fine-grained, configurable logging of security-relevant events, and is intended to meet the requirements of the Common Criteria (CC) Common Access Protection Profile (CAPP) evaluation. The Fx facility implements the de facto industry standard BSM API, file formats, and command line interface, first found in the Solaris operating system. Information on the user space implementation can be found in libbsm(3).

Audit support is enabled at boot, if present in the kernel, using an rc.conf5 flag. The audit daemon, auditd(8), is responsible for configuring the kernel to perform , pushing configuration data from the various audit configuration files into the kernel.

Audit Special Device

The kernel facility provides a special device, /dev/audit which is used by auditd(8) to monitor for events, such as requests to cycle the log, low disk space conditions, and requests to terminate auditing. This device is not intended for use by applications.

Audit Pipe Special Devices

Audit pipe special devices, discussed in auditpipe(4), provide a configurable live tracking mechanism to allow applications to tee the audit trail, as well as to configure custom preselection parameters to track users and events in a fine-grained manner.


The OpenBSM implementation was created by McAfee Research, the security division of McAfee Inc., under contract to Apple Computer Inc. in 2004. It was subsequently adopted by the TrustedBSD Project as the foundation for the OpenBSM distribution.

Support for kernel first appeared in Fx 6.2 .


An -nosplit This software was created by McAfee Research, the security research division of McAfee, Inc., under contract to Apple Computer Inc. Additional authors include An Wayne Salamon , An Robert Watson , and SPARTA Inc.

The Basic Security Module (BSM) interface to audit records and audit event stream format were defined by Sun Microsystems.

This manual page was written by An Robert Watson Aq [email protected] .


The Fx kernel does not fully validate that audit records submitted by user applications are syntactically valid BSM; as submission of records is limited to privileged processes, this is not a critical bug.

Instrumentation of auditable events in the kernel is not complete, as some system calls do not generate audit records, or generate audit records with incomplete argument information.

Mandatory Access Control (MAC) labels, as provided by the mac(4) facility, are not audited as part of records involving MAC decisions.