ModSecurity WAF (Web Application Firewall ) is an open source software firewall that is used to safeguard applications from attacks & unauthorised access. ModSecurity WAF can be used as a module with already installed Apache web server or also with Nginx server or IIS. It continuously checks the incoming traffic & performs real time analysis .

The best feature that makes ModSecurity wonderful is that it supports flexible rule engine using which we can safeguard our applications from a number of threats like XSS attacks, SQL injection attacks, Local file include, remote file include attacks etc.