ModSecurity is a powerful web app layer firewall for Apache web servers. It monitors the entire HTTP traffic to a site without affecting its overall performance and if it discovers an intrusion attempt, it prevents it. The firewall also maintains a more detailed log for the site visitors than any web server does, so you'll manage to monitor what is going on with your sites a lot better than if you rely only on conventional logs. ModSecurity employs security rules based on which it stops attacks. For example, it detects if someone is attempting to log in to the administration area of a particular script a number of times or if a request is sent to execute a file with a specific command. In these circumstances these attempts trigger the corresponding rules and the software blocks the attempts in real time, and then records comprehensive info about them within its logs. ModSecurity is one of the best software firewalls on the market and it can easily protect your web applications against many threats and vulnerabilities, particularly in case you don’t update them or their plugins frequently.