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Web filter

Web filter

(also content filter or URL filter)

Web filter definition

A web filter is a software tool that manages access to websites and other types of online content based on predefined rules. Businesses and schools may use web filtering for various reasons — from making networks more secure to boosting employee and student productivity. Web filtering may restrict access to all kinds of platforms, from social media networks to gambling sites.

See also: web content filtering

How web filters work

1. When you attempt to access a website or an online resource, your request is broken down into data packets sent over the internet.
2. Web filters use predefined criteria to review and check the data packet content. These rules can be based on URLs, keywords, IP addresses, and content type (e.g., adult content).
3. The web filter compares the content to its predefined rules. Based on these rules, it may allow the content to pass through, block it, redirect the user to a warning page, or log the activity).
4. Web filters need regular updates to stay effective — websites and content can change, with new threats or inappropriate content becoming a problem.
5. In some cases, web filters may integrate with user authentication systems, allowing organizations to apply different filtering rules to users or groups based on their permissions.

Web filter types

• URL filters may block websites based on their web addresses.
• Content filters analyze the content of web pages to determine if it should be allowed or blocked.
• DNS filters block access to specific domains at the DNS level.
• Application filters control access to specific web applications and services.
• Malware filters identify and block websites that are known sources of malware.
• Protocol filters control access to specific internet protocols or services.
• Behavioral filters analyze user behavior and identify potential harmful activity.