ModSecurity is a powerful web app layer firewall for Apache web servers. It monitors the whole HTTP traffic to a website without affecting its performance and when it discovers an intrusion attempt, it prevents it. The firewall also keeps a more comprehensive log for the traffic than any server does, so you'll manage to monitor what's going on with your websites a lot better than if you rely simply on standard logs. ModSecurity uses security rules based on which it helps prevent attacks. For example, it recognizes if someone is trying to log in to the administration area of a given script multiple times or if a request is sent to execute a file with a certain command. In these instances these attempts set off the corresponding rules and the firewall software blocks the attempts in real time, and then records detailed information about them in its logs. ModSecurity is among the very best software firewalls on the market and it can easily protect your web apps against a huge number of threats and vulnerabilities, particularly if you don’t update them or their plugins frequently.