FileTraq

FileTraq is a shell script designed to be run periodically from the root crontab. Each time, it compares a list of system files with the copies that it keeps. Any changes are reported in diff or patchfile style, and dated backup copies are kept. It lets you keep an eye on intruders who might change system files, or other sysadmins who don't tell you about changes. It even helps you keep track of your own changes, along with dated backups.