ModSecurity

see wikipedia article

ModSecurity, sometimes called Modsec, is an open-source web application firewall (WAF). Originally designed as a module for the Apache HTTP Server, it has evolved to provide an array of Hypertext Transfer Protocol request and response filtering capabilities along with other security features across a number of different platforms including Apache HTTP Server, Microsoft IIS and NGINX. It is a free software released under the Apache license 2.0.

Interesting rulesets

Categories waf