ModSecurity is a highly effective firewall for Apache web servers which is employed to stop attacks against web applications. It monitors the HTTP traffic to a particular 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 - as an illustration, attempting to log in to a script admin area without success many times sets off one rule, sending a request to execute a certain file that could result in getting access to the website triggers a different rule, etcetera. ModSecurity is among the best firewalls out there and it will preserve even scripts which aren't updated on a regular basis since it can prevent attackers from using known exploits and security holes. Incredibly comprehensive data about every single intrusion attempt is recorded and the logs the firewall maintains are far more comprehensive than the regular logs provided by the Apache server, so you may later take a look at them and determine whether you need to take additional measures in order to improve the protection of your script-driven sites.