ModSecurity is a powerful firewall for Apache web servers which is used to stop attacks against web apps. It keeps track of the HTTP traffic to a given site in real time and prevents any intrusion attempts as soon as it discovers them. The firewall relies on a set of rules to accomplish that - as an example, trying to log in to a script admin area unsuccessfully many times sets off one rule, sending a request to execute a specific file which could result in getting access to the Internet site triggers a different rule, and so forth. ModSecurity is one of the best firewalls available and it will preserve even scripts that are not updated on a regular basis because it can prevent attackers from employing known exploits and security holes. Very detailed info about every single intrusion attempt is recorded and the logs the firewall keeps are much more detailed than the regular logs generated by the Apache server, so you may later examine them and determine whether you need to take more measures in order to improve the security of your script-driven Internet sites.