ModSecurity is a powerful firewall for Apache web servers that is used to prevent attacks toward web applications. It keeps track of the HTTP traffic to a certain Internet site in real time and blocks any intrusion attempts the moment it detects them. The firewall uses a set of rules to do this - for instance, attempting to log in to a script administration area unsuccessfully several times sets off one rule, sending a request to execute a specific file which may result in accessing the Internet site triggers a different rule, and so forth. ModSecurity is one of the best firewalls on the market and it will protect even scripts which aren't updated regularly since it can prevent attackers from employing known exploits and security holes. Quite comprehensive information about each intrusion attempt is recorded and the logs the firewall keeps are much more comprehensive than the regular logs created by the Apache server, so you may later examine them and determine whether you need to take additional measures in order to increase the security of your script-driven sites.