Tripwire is a file and directory integrity checker, a utility that
compares a designated set of files and directories against information
stored in a previously generated database.  Any differences are
flagged and logged, including added or deleted entries.  When run
against system files on a regular basis, any changes in critical
system files will be spotted -- and appropriate damage control
measures can be taken immediately.  With Tripwire, system
administrators can conclude with a high degree of certainty that a
given set of files remain free of unauthorized modifications if
Tripwire reports no changes.