webfiltering

Web filtering refers to the process of controlling access to web content by evaluating requests to access websites and applying policies. It is used by organizations, schools, and households to enforce acceptable use, protect users from threats, and comply with regulatory requirements.

Filtering is achieved through several techniques: URL filtering (blocking specific sites), category filtering (blocking sites by categories such as adult content or gambling), keyword filtering (blocking based on terms), reputation-based filtering, and protocol or DNS filtering. Many implementations use proxies or gateways that inspect traffic and apply allow/deny lists or policy-based rules. Some solutions operate at the endpoint, on appliances, or as cloud services.

Types and scope: enterprise web filters, consumer parental controls, and secure web gateways that combine filtering with threat protection. Implementations may rely on white lists (allow) or black lists (block). Use cases include productivity and safety, regulatory compliance, and bandwidth management. They may also include data loss prevention and malware/phishing protection, sometimes scanning TLS-encrypted traffic.

Limitations include overblocking or underblocking, privacy concerns, and susceptibility to evasion via VPNs or encrypted traffic. Encryption and HTTPS make inspection harder; privacy laws and user consent impact deployment. False positives can disrupt legitimate work.

History and trends: from early proxy-based filtering in the 1990s to modern cloud-based services and Secure Web Gateways. Emerging trends include real-time threat intelligence, AI-assisted categorization, and integration with cloud access security brokers.