ModSecurity is an efficient firewall for Apache web servers which is employed to prevent attacks toward web apps. It keeps track of the HTTP traffic to a particular site in real time and stops any intrusion attempts the instant it discovers them. The firewall relies on a set of rules to do this - for instance, attempting to log in to a script administration area unsuccessfully many times activates one rule, sending a request to execute a particular file that may result in accessing the website triggers a different rule, and so on. ModSecurity is one of the best firewalls available and it'll secure even scripts which are not updated often because it can prevent attackers from using known exploits and security holes. Very comprehensive data about every single intrusion attempt is recorded and the logs the firewall keeps are much more specific than the standard logs created by the Apache server, so you could later examine them and decide whether you need to take more measures so as to boost the security of your script-driven Internet sites.