Application Performance Monitoring with PasTmon
by Kerry Thompson in Sys Admin Magazine July 2007.

Measure the transaction response times of your web and application servers. Performing continuous passive monitoring of network traffic. Recording historical data of measurements in a backend database and presenting via a PHP/Jpgraph based web front-end.
PasTmon is a passive network traffic analyser that can measure user transaction response times of web, ftp, dns, irc, pop, mail, postgresql, and mysql database servers. You can even define your own signature rules to monitor custom TCP based applications. PasTmon is a server administrator’s tool for measuring application performance and response times.
PasTmon is Open Source and licensed under the GNU General Public License. It is available for Linux/Unix systems, is free to download, use and tailor to your needs.

Note: The URL www.pastmon.org will be allowed to expire early 2009, please update your bookmarks/favorites to use http://pastmon.sourceforge.net/