Install ModSecurity

[auryn]

ModSecurity is a web application layer firewall which protects your server from script exploits found in web applications. It seems like a great tool you can use to tighten security. It adds another layer of protection in addition to your network firewall.

For a brief guide that should help you get ModSecurity installed on a dedicated server running CentOS:

Red Hat / CentOS Install mod_security Apache Intrusion Detection And Prevention Engine