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.
Firewall Builder consists of a GUI and set of policy compilers for various firewall platforms. It helps users maintain a database of objects and allows policy editing using simple drag-and-drop operations. The GUI and policy compilers are completely independent, which provides for a consistent abstract model and the same GUI for different firewall platforms. It currently supports iptables, ipfilter, ipfw, OpenBSD pf, Cisco PIX and FWSM, and Cisco routers access lists.
FSlint is a toolkit to find various forms of lint on a filesystem. At the moment it reports duplicate files, bad symbolic links, troublesome file names, empty directories, non stripped executables, temporary files, duplicate/conflicting (binary) names, and unused ext2 directory blocks.