What Is URL Filtering? URL filtering is a means of preventing access to particular web content through an organization’s network or endpoints. This generally includes blocking malicious websites to protect users and endpoints from cyberattacks. Organizations also often use URL filtering to restrict specific URLs or URL categories that tend to use high bandwidth or hamper productivity, such as social media and video streaming sites.

Why Is URL Filtering Important?

URL filtering is a key element of web security that allows organizations to configure how their users access webpages through a network or other systems. It can help to:

• Protect users and data from internet-based security threats such as phishing sites, ransomware, and other malware
• Reduce bandwidth usage and improve productivity by restricting access to non-work-related sites or apps
• Limit the organization’s exposure to liability by blocking access to inappropriate content

Before we continue, let’s clarify some important terms.

What Is a URL?

A Uniform Resource Locator, or URL, is an address that corresponds to the location of a website, database, web application, or protocol (among other things), allowing a web browser to retrieve it.

What’s the Difference Between Web Filtering, URL Filtering, and DNS Filtering?

Web filtering is a broad term that encompasses multiple methods of controlling the sites and web apps users can access online. URL filtering and DNS filtering are two such methods.

In short, URL filtering blocks URLs (individual webpages) while DNS filtering blocks DNS requests and therefore IP addresses (whole websites).

How Does URL Filtering Work?

URL filtering works by applying granular policies that allow or restrict access to particular URLs. These policies can be based on multiple criteria, such as URL categories, specific users or user groups, departments, locations, and time intervals.

When an end user tries to access any URL, the request is compared in real time against active URL filtering policies to determine whether the request should be allowed. If access is granted, the page loads normally. If access is denied, the page is prevented from loading, and the user is instead shown a “block” notification.

Disadvantages of URL Filtering

Although not a functional disadvantage of URL filtering itself, improper policy configuration can lead to over-filtering. For instance, blocking YouTube to keep developers from getting distracted could also stop them from watching video tutorials, which would slow them and your organization down while potentially creating more work for your IT helpdesk.

It’s also worth noting that URL filtering alone is not a comprehensive internet security strategy. Modern threat actors can develop new URLs and IP addresses extremely quickly, requiring security strategies that go above and beyond simple block and allow lists of known malicious sites.

How Does URL Filtering Help Block Malware and Phishing?

URL categorization includes much more than just topic tags like “shopping” or “finance.” For example, most URL filtering services integrate with a threat intelligence database to block URLs flagged as exploitive, malicious, or otherwise dangerous, such as those associated with malware campaigns or phishing attacks.

This is just one of various functions that work together to give security teams precise control over web access—let’s take a look at these next.

Key Features of URL Filtering

Basic URL filtering solutions allow administrators to customize simple allow and/or block lists to block access to undesired or malicious URLs. Today’s advanced URL filtering tools include these features and more, allowing you to configure:

• Granular, modular policies: Effective URL filtering policies can be molded to suit the needs and restrictions of multiple groups across an organization. For example, an HR team might need unrestricted access to LinkedIn, but an IT team might not.
• “Allow” and “block” actions: The basic “green light” and “red light” actions of URL filtering permit or deny access according to policy.
• “Caution” action: Unlike a block, this action informs a user of potential security risks associated with a request and allows the user to decide whether or not to proceed.
• “Override” action: Generally reserved for advanced or administrative users, the option to override enables a “block” rule to be bypassed altogether.
• Duration and bandwidth quotas: Administrators can specify limits on bandwidth consumed and browsing time, after which the action for that URL will change to a more restrictive one (i.e., “caution” or “block”).

How Zscaler Can Help

Zscaler offers powerful URL filtering as a native feature of Zscaler Internet Access™ (ZIA™), the world’s most deployed security service edge (SSE) platform, along with our industry-leading secure web gateway, data loss prevention, cloud-gen firewall, and more.

Zscaler Internet Access is part of the comprehensive Zscaler Zero Trust Exchange™ platform, which enables fast, secure connections to allow your employees to work from anywhere using the internet as the corporate network.

Key Benefits of URL Filtering from Zscaler

Through native integration with our entire ecosystem, Zscaler URL filtering offers peerless control over your web traffic, including:

• Dynamic content categorization: Leverage machine learning to determine if uncategorized URLs belong to specific URL categories and apply policy accordingly.
• Integrated browser isolation: Isolate all traffic to URLs in selected categories through native integration with Zscaler Cloud Browser Isolation.
• Embedded sites categorization: Enforce URL filtering policy for sites translated through services such as Google Translate.
• Safe search enforcement: Enforce safe results on search engine queries when SSL inspection is enabled by leveraging Zscaler’s unmatched scalability.
• Granular productivity app controls: Simplify configuration, restrict tenants, and control allowed domains for Microsoft 365 and Google Workspace apps.