ModSecurity is a plugin for Apache web servers that functions as a web application layer firewall. It is employed to stop attacks towards script-driven Internet sites through the use of security rules which contain particular expressions. In this way, the firewall can stop hacking and spamming attempts and preserve even websites that are not updated on a regular basis. For example, multiple failed login attempts to a script admin area or attempts to execute a certain file with the intention to get access to the script will trigger particular rules, so ModSecurity shall stop these activities the second it detects them. The firewall is very efficient since it monitors the entire HTTP traffic to an Internet site in real time without slowing it down, so it can easily prevent an attack before any damage is done. It also maintains an exceptionally comprehensive log of all attack attempts which includes more information than standard Apache logs, so you can later analyze the data and take further measures to boost the security of your websites if needed.