1. Overview FortiGuard Web Filtering is a cloud-based security service integrated into Fortinet’s FortiGate firewalls. It categorizes millions of websites (e.g., Social Media, Malware, Phishing, Adult, Streaming) and enforces access policies. When a site is blocked, users see a FortiGuard Block Page with a reason and a FortiGuard category (e.g., Category 48 – Bandwidth Wasting ).