FreeBSD 6.2 and later include support for fine-grained security event auditing. Event
auditing allows the reliable, fine-grained, and configurable logging of a variety of
security-relevant system events, including logins, configuration changes, and file and
network access. These log records can be invaluable for live system monitoring, intrusion
detection, and postmortem analysis. FreeBSD implements Sun™'s published BSM
API and file format, and is interoperable with both Sun's
Solaris™ and Apple®'s Mac OS® X
audit implementations.
This chapter focuses on the installation and configuration of Event Auditing. It
explains audit policies, and provides an example audit configuration.
After reading this chapter, you will know:
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What Event Auditing is and how it works.
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How to configure Event Auditing on FreeBSD for users and processes.
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How to review the audit trail using the audit reduction and review tools.
Before reading this chapter, you should:
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Understand UNIX® and FreeBSD basics (Chapter 3).
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Be familiar with the basics of kernel configuration/compilation (Chapter 8).
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Have some familiarity with security and how it pertains to FreeBSD (Chapter 14).
Warning: The audit facility in FreeBSD 6.X
is experimental, and production deployment should occur only after careful consideration
of the risks of deploying experimental software. Known limitations include that not all
security-relevant system events are currently auditable, and that some login mechanisms,
such as X11-based display managers and third party daemons, do not properly configure
auditing for user login sessions.
Warning: The security event auditing facility is able to generate very detailed
logs of system activity: on a busy system, trail file data can be very large when
configured for high detail, exceeding gigabytes a week in some configurations.
Administrators should take into account disk space requirements associated with high
volume audit configurations. For example, it may be desirable to dedicate a file system
to the /var/audit tree so that other file systems are not
affected if the audit file system becomes full.
