What is Web Filtering?

Boost your organization’s cybersecurity knowledge with this web filtering glossary. Learn how web filters can protect your network from cyber threats.

What is Web Filtering?

A web filter is a software that ensures safer internet browsing by controlling or restricting access to harmful, inappropriate, or distracting websites and content. It can also help organizations block unauthorized entry to websites by threat actors. Filtering can be implemented at various levels, from individual devices to entire networks.

The Benefits of Web Filtering

Web filtering can protect users against explicit or malicious content and websites, enhance workplace productivity, and provide worry-free access to relevant, appropriate, and useful information. Filtering provides many benefits for home, school, and organizational use, including:

• Protection against malware and phishing – Web filtering can help prevent users from accessing websites that are known to distribute malware or engage in phishing attacks, reducing the risk of viruses and cyberattacks.
• Enhanced productivity – By limiting access to potentially distracting websites and content, a filter can reduce distractions and improve employee or student focus and productivity.

• Regulatory compliance – Web filtering can help organizations comply with industry regulations, especially those prioritizing privacy, such as HIPAA, PCI-DSS, and CIPA, by blocking access to certain types of websites and content.

• Increased data security – With filtering, organizations can protect sensitive documents and information from theft, interception, and eavesdropping by limiting access to public file-sharing networks and unencrypted websites.

• Improved network performance – In organizations with high web traffic, filtering can help to reduce bandwidth usage. For example, blocking access to high-bandwidth websites such as video streaming sites and file-sharing networks can improve overall network performance.

• Protection against inappropriate content – Online filtering can help protect children and other vulnerable individuals from accessing inappropriate or explicit content online.

• Legal protection – Organizations can use filtering to protect themselves from legal liability by preventing users from accessing websites and content that may be illegal or inappropriate.

Overall, a web filter can help organizations protect their networks, reduce the risk of data breaches and cyber attacks, increase productivity, and comply with regulations. At the same time, filtering can improve users’ online experiences.

Types of Web Filtering

There is no one-size-fits-all approach to online filtering. However, there are several ways organizations can use it to control access to potentially harmful content and websites:

• Server-side filtration – Server-side filtering is often used in large organizations because it can handle filtering requests from multiple users. It utilizes a server such as a proxy or a firewall to filter requests based on predetermined criteria like URL, content type, or category. The server can then allow or block requests as appropriate.
• Client-side filtration – Client-side filtering originates on a user’s device, working through software or browser extensions to block specified websites or content.
• ISP-level filtration – ISP filtering is performed by a user’s Internet Service Provider (ISP) and is often used by governments and institutions. Restrictions are set at the ISP level to block access to malicious websites, prevent cyber attacks, and comply with regulatory requirements.
• DNS Filtering – This method blocks the DNS lookup requests for specific domain names, preventing the browser from connecting to the website. DNS filtering can block access to specific categories of websites, such as gambling, social media, or streaming services. It is also used to prevent malware infections and phishing attacks.
• Content filtering – Content filtering analyzes website content based on predefined filters such as keywords, phrases, or file types and determines whether or not to provide access.
• Allow lists – Allow lists (or white lists) are a type of filtering that only allow access to pre-approved websites or domains. Websites or domains not on the allow list are automatically blocked, preventing users from accessing them. 
• Block lists – Block lists (or black lists) are a type of filtering that blocks access to specific websites or domains that are considered harmful or inappropriate. Websites or domains on the block list are automatically prevented from being accessed. 

The choice of the right method will depend on the specific needs of the organization or individual. A combination of different filtering methods may be necessary to provide comprehensive protection against cyber threats and enforce security policies effectively.

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Web Filtering Use Cases

Web filtering can be used in any situation where monitoring access to online content would be beneficial. Here are some examples:

• Block Malicious Downloads – Web filtering can be used as a cybersecurity measure to block users from downloading potentially damaging malware. 

• Guard Against Credential Phishing – Likewise, blocking access to phishing websites can prevent unauthorized access and attempts to steal personal or sensitive information. Since many data breaches and cyberattacks originate with email phishing attempts, businesses of all sizes can benefit from filtering services that block malicious links and inform users when they are detected.

• Block Questionable Content – This type of filtering is often used by parents and school districts, whose goal is web safety for children and youth browsing the internet. Similarly, employers may use online filtering to increase employee productivity by restricting access to potentially distracting content found on online shopping, social media, or gaming sites. Individuals can also use web filtering to limit screen time and monitor online activities.

• Restrict Access to Certain Accounts – Enterprises or organizations in regulated industries may rely on website filtering to define roles and grant access to sensitive data only to those employees who need it to perform their job duties. Limiting access to certain resources can also help businesses save money by reducing the number of required software licenses or subscriptions.

Web filtering can be used in various scenarios to control access to online content. By restricting access to specific websites and online content, organizations can prevent unauthorized access, increase productivity, ensure compliance, and protect against cyber threats.

Unlock the Best Web Filter with Perimeter81

Unfortunately, employees, students, and bad actors may try to find workarounds that trick web filtering systems and allow them to access blocked websites. Strategies like these violate organizational policies and may even be illegal in some areas:

• Using a VPN or a web proxy to act as an intermediary between the user’s device and the destination website and mask the content being returned to the user.
• Using the cached version of a website saved in an internet browser
• Using a URL shortener like Bit.ly or TinyURL
• Using the blocked website’s IP address
• Using the HTTP version of a blocked website instead of HTTPS 
• Using a browser extension that allows you to bypass web filters
• Using an open-source browser like Tor that hides your IP address and allows you to access unauthorized content like dark websites

Fortunately, a robust web filtering solution like Perimeter81 can anticipate and prevent access for those attempting to use these approaches. Filtering systems may use category blocking and application controls to block access to VPNs, proxy servers, and Tor.

Likewise, SSL inspections and IP blockers can prevent inauthentic use of HTTP/HTTPS and block access to specific IP addresses known to bypass web filters. Finally, comprehensive filtering tools monitor user behavior, alert administrators of attempts to bypass web filters and identify specific users who violate the rules.

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