mod_security

http://www.packtpub.com/article/ways-improve-performance-server-in-modsecurity2.5

http://blog.spiderlabs.com/2011/08/modsecurity-advanced-topic-of-the-week-exception-handling.html

http://www.symantec.com/connect/articles/web-security-appliance-apache-and-modsecurity

http://www.packtpub.com/article/ways-improve-performance-server-in-modsecurity2.5