ModSecurity2 is an open source web application firewall
that runs as an Apache2 module.


Links
------
Home page: http://www.modsecurity.org/

Brief ModSecurity2 introduction and feature's list:
http://www.modsecurity.org/documentation/ApacheCon_Europe_2008-Web_Intrusion_Detection_with_ModSecurity.pdf

Documentation:
http://www.modsecurity.org/documentation/

FAQ:
http://www.modsecurity.org/documentation/faq.html



Additional resources
--------------------
Got Root project: a huge set of web application firewall signatures:
http://www.gotroot.com/mod_security+rules

ScallyWhack project: set of rules to block spam posted to
Trac-driven websites:
http://projects.otaku42.de/wiki/ScallyWhack