What is a WAF (Web Application Firewall)?

WAF (Web Application Firewall) is a specialized firewall that filters, monitors, and blocks HTTP traffic to web applications. The main task of WAF is to protect web applications from various attacks such as SQL injections, XSS (cross-site scripting), CSRF, application vulnerability attacks, and other threats at the application level.

WAF operates at the application layer (layer 7 of the OSI model), analyzing incoming requests and outgoing responses, applying a set of security rules and policies. It can be implemented as software, hardware, or a cloud service.

Example of use: if a user attempts to send malicious script to an input form, WAF can recognize this request and block it, preventing the attack.