ModSecurity is a powerful firewall for Apache web servers that is used to stop attacks towards web apps. It monitors the HTTP traffic to a particular Internet site in real time and prevents any intrusion attempts the moment it discovers them. The firewall relies on a set of rules to do this - for instance, attempting to log in to a script administrator area without success a few times triggers one rule, sending a request to execute a particular file that could result in accessing the Internet site triggers another rule, and so on. ModSecurity is one of the best firewalls out there and it will preserve even scripts which aren't updated often since 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 considerably more comprehensive than the standard logs generated by the Apache server, so you can later take a look at them and decide whether you need to take extra measures so as to boost the security of your script-driven websites.