The audit package contains the user-space utilities for creating audit rules, as well as for storing, searching, and generating reports from the audit records generated by the audit subsystem in the Linux 2.6 kernel and higher. It has a real-time plugin interface for event analysis and remote logging of events.
AIDE (Advanced Intrusion Detection Environment) is a file and directory integrity checker. It creates a database from the regular expression rules that it finds from the config file. Once this database is initialized it can be used to verify the integrity of the files. Several message digest algorithms are used. All of the usual file attributes can also be checked for inconsistencies.