ModSecurity is a highly effective firewall for Apache web servers that is employed to stop attacks toward web apps. It monitors the HTTP traffic to a specific Internet site in real time and stops any intrusion attempts the moment it identifies them. The firewall relies on a set of rules to do that - for example, trying to log in to a script administration area unsuccessfully several times activates one rule, sending a request to execute a certain file that may result in accessing the website triggers another rule, etcetera. ModSecurity is one of the best firewalls out there and it will protect even scripts which aren't updated on a regular basis because it can prevent attackers from employing known exploits and security holes. Very comprehensive information about every intrusion attempt is recorded and the logs the firewall keeps are considerably more detailed than the conventional logs created by the Apache server, so you can later take a look at them and decide whether you need to take additional measures in order to boost the security of your script-driven Internet sites.