ModSecurity is a plugin for Apache web servers that acts as a web app layer firewall. It is employed to stop attacks against script-driven Internet sites by using security rules that contain certain expressions. In this way, the firewall can stop hacking and spamming attempts and shield even websites which are not updated frequently. For example, several failed login attempts to a script admin area or attempts to execute a specific file with the objective to get access to the script shall trigger specific rules, so ModSecurity will stop these activities the instant it detects them. The firewall is quite efficient since it screens the entire HTTP traffic to an Internet site in real time without slowing it down, so it can easily stop an attack before any damage is done. It also keeps an exceptionally detailed log of all attack attempts that includes more information than traditional Apache logs, so you could later check out the data and take extra measures to increase the security of your Internet sites if necessary.