ModSecurity is a powerful firewall for Apache web servers which is used to prevent attacks toward web apps. It keeps track of the HTTP traffic to a given Internet site in real time and blocks any intrusion attempts the moment it discovers them. The firewall uses a set of rules to do that - for example, attempting to log in to a script administration area unsuccessfully several times sets off one rule, sending a request to execute a certain file which may result in accessing the website triggers another rule, etc. ModSecurity is one of the best firewalls available and it will preserve even scripts which aren't updated often as it can prevent attackers from employing known exploits and security holes. Quite comprehensive information about every intrusion attempt is recorded and the logs the firewall keeps are a lot more detailed than the conventional logs generated by the Apache server, so you can later take a look at them and decide if you need to take additional measures in order to boost the security of your script-driven websites.