logsurfer is a log checking/auditing tool similar to swatch and logcheck but with the capability of handling multi-line messages and dynamically adapting the ruleset. It is written in portable C, well documented, fast, and flexible. It works on any textfile or stdin, can be run at intervals or continuously, and has timeouts and resource limits.
NewSyslog is an updated version of a package put together by Theodore Tso of MIT Project Athena (which is included in NetBSD, FreeBSD, OpenBSD, etc.). It manages the rotation and archiving of log files (primarily those written to by syslogd). This version has a mix of features from all of the other versions, and it has been made more portable than any of the others with the help of GNU Autoconf.
Xtradius is a radius server that permits you to handle user authentication and accounting request via external scripts. You can handle script requests for user accounting, user authentication, NAS start and NAS stop packets. You can also write additional information into the NAS detail logfile. Parameters to scripts are passed via command line options or environment variables, making it very simple to implement SQL-based user accounting, authentication and account expiration. It is also compatible with "standard" cistron radius server.
Sniff formats hex packets from the tcpdump program and converts them to ASCII to make them easier to read and understand. Its features include colored console output, CSV file saving, and fully customizable output. The program directly accepts all tcpdump options, including parsing from packet files.