ModSecurity is a plugin for Apache web servers that functions as a web app layer firewall. It's employed to stop attacks toward script-driven websites through the use of security rules that contain particular expressions. That way, the firewall can prevent hacking and spamming attempts and protect even sites which are not updated on a regular basis. As an example, multiple unsuccessful login attempts to a script administrative area or attempts to execute a specific file with the objective to get access to the script shall trigger certain rules, so ModSecurity shall block these activities the instant it discovers them. The firewall is incredibly efficient since it monitors the entire HTTP traffic to a site in real time without slowing it down, so it will be able to stop an attack before any damage is done. It also maintains an exceptionally comprehensive log of all attack attempts which features more info than traditional Apache logs, so you can later analyze the data and take additional measures to improve the security of your Internet sites if necessary.