ModSecurity is a powerful firewall for Apache web servers that is employed to prevent attacks towards web applications. It monitors the HTTP traffic to a given Internet site in real time and blocks any intrusion attempts the moment it discovers them. The firewall relies on a set of rules to accomplish that - for example, attempting to log in to a script administrator area unsuccessfully many times triggers one rule, sending a request to execute a certain file which may result in accessing the Internet site triggers another rule, and so on. ModSecurity is one of the best firewalls on the market and it will secure even scripts that aren't updated often since it can prevent attackers from using known exploits and security holes. Quite comprehensive info about each intrusion attempt is recorded and the logs the firewall keeps are much more detailed than the standard logs provided by the Apache server, so you may later examine them and determine if you need to take extra measures in order to enhance the protection of your script-driven Internet sites.