ModSecurity
ModSecurity is a web application firewall. ModSecurity offers real time web application monitoring and access control. It can also be used as a logging tool and it understands the HTTP traffic better than traditional firewalls. If it detects any malicious traffic it blocks it. It offers a continuous security assessment passively. As ModSecurity is integrated with AV scanning, it can detect malicious files which are uploaded through web application. It can also detect wrongly configured applications and alerts the user regarding it.