Skip to content Skip to navigation Skip to footer

What Is Content Filtering?

Content Filtering: Definition

Content filtering is a process that manages or screens access to specific emails or webpages. The goal is to block content that contains harmful information. Content filtering programs are commonly used by organizations to control content access through their firewalls. They can also be used by home computer users.

Content filtering can be implemented as hardware or software and is often built into internet firewalls to block access to information. Companies use content filtering tools to bolster security and enforce corporate policies around information system management, such as when filtering social networking sites.

Why Is Content Filtering Important?

Content filtering prevents access to content that could pose a risk to internet users. It blocks access to content deemed illegal, inappropriate, or objectionable. 

For example, it allows individual internet users to protect children from exposure to graphic or improper material. It also enables an organization to block access to pornographic content, which, when left unmitigated, could lead to sexual harassment claims or a demeaning work environment.

Further examples of the importance of content filtering include:

Minimize Malware Attacks

Content filters allow organizations to block access to sites known to carry malware, protecting their data and users from malicious activity in the process. For example, Domain Name System (DNS) filtering can limit and block the threat of internet-borne malware and reduce the remediation time and workload necessary in case malware penetration occurs. Firewalls that contain content filtering features can also scan and scrutinize webpages to monitor for threats.

Organizations should educate their employees on the threat of malware and phishing attacks. User knowledge can make a significant difference in the effectiveness of attacks and limit the chances of employees visiting risky sites.

Protection from Exploit Kits

Cyber criminals increasingly develop new, more sophisticated ways of illegally accessing networks and stealing data. Exploit kits contain code that enables a malicious actor to attack web browser vulnerabilities through extensions and plugins. This can lead users to unknowingly visit malicious websites, which may trigger a malware download. Content filters can identify an exploit kit and block access before it triggers a download.

Hybrid Data Center

Boost Network Bandwidth

Use of the internet for activity that is not work-related can significantly affect an organization’s network bandwidth. Limiting users’ access to specific websites, such as video streaming sites like YouTube, can increase bandwidth efficiency and enable faster connections for all employees.

Increase Staff Productivity

Popular websites, such as social media, online shopping, and streaming channels, are big productivity killers. They take up vast amounts of users’ time. Organizations can use content filters to restrict access to such sites and increase staff productivity levels. They can also block access to websites considered distracting or dangerous.

How Does Content Filtering Work?

Content filtering software and hardware work by identifying and blocking access to specific content or websites. An excellent example of how content filtering works is identifying specific patterns in content, such as strings of text or objects in images, that signify the presence of undesirable content. Content filters typically use keywords to block access to webpages, and in some cases, entire websites. 

Organizations commonly use DNS filtering to block access to specific Internet Protocol (IP) addresses, e-commerce websites, social media sites, and streaming services.

How to Remove Content Filtering

Content filtering helps users stay safe on the internet. However, it can also block access to legitimate sites or those required for work. For example, the website could be blocked by certain content filtering firewall rules. To prevent this, internet users can remove content filtering by disabling it on their router or through their search engine. 

Steps are as follows:

Steps for Disabling router-based Content Filters

To enable access to specific sites by disabling a router-based content filter:

  1. Log in to the router’s network configuration utility, then open the main settings file.
  2. Select the “Blocked sites” section.
  3. Click the filter that needs to be removed and select either “Delete” or “Disable.”
  4. Click on the "Apply" button. The content filter should now be disabled.
  5. Log out of the router’s network configuration settings.

Steps for Disabling Search Engine Filters

Content filters can also be applied via Google Safe Search, which can only be amended by administrators. Once the filter setting has been changed, it will only be accessible by entering a password. Furthermore, search settings tend to block vast chunks of content without specification. 

To disable these filters:

  1. Visit the Google search preferences page and navigate to “Resources” to find the appropriate web address.
  2. Scroll down to the “Safe Search filters” option, and click the filter off so that it reads “No filtering.”
  3. Click the "Save" button, and the change should now be active.

Do Content Filters Always Exhibit Foolproof Capabilities?

As online threats multiply, content filters provide organizations and individuals alike with a crucial first line of defense. However, a content filtering router is not always foolproof, and it can make mistakes. For starters, it is almost impossible for content filters to block all unwanted content, considering the public web contains more than 4.5 billion websites. Furthermore, they can often block important resources and content that users need to work effectively.

Content filters that apply stricter rule settings can end up blocking innocuous or legitimate sites or those that may appear political. Given these issues, it is often best to look for a comprehensive content filter that enables regular updates and allows changes where necessary. 

Types of Content Filters

Content filters are used in different ways and to block access to different types of material. Common types of content filters include:

Internet Filters

Internet filters are the most common form of content filter, blocking access to specific internet pages or entire websites. These are managed through firewalls providing internet access or through browser-based filters, which are implemented through browser extensions.

Search Engine Filters

A search engine content filter enables users to activate settings that filter out inappropriate items from search results. Users can also use these to block the Uniform Resource Locator (URL) of a website they know to contain adult, explicit, or inappropriate content. Some search engines also provide child-oriented filter versions that only permit access to child-friendly content and websites.

Hybrid Data Center

DNS-based Content Filtering

This form of content filtering occurs at the DNS layer to block domains that do not fit policies defined by an organization’s corporate rules. Parental control settings can also be implemented through DNS-based content filtering. 

Email Filters

Email-based content filtering identifies information in the body, header, subject, and attachments of email messages. This enables users to block malicious emails, or accept, classify, and reject incoming mail.

Web Filters

Web content filtering prevents users from accessing or viewing specific URLs by blocking their browser from loading certain sites. Web filters can also block content based on the quality of a website using lists that categorize content.

Proxy Content Filtering

A proxy filter acts as a middleman between a user’s device and the server. It can be used as a gateway between network users and the public internet, which enables admins to filter, customize, and restrict access to specific websites. This is commonly used in schools to provide different access levels for teachers and pupils. Governments have also used proxy content filtering to prevent citizens from accessing websites they deem unpatriotic or against their ideology.

Content Filtering Best Practices in 2021

  1. Enable remote deployment: As people increasingly work from disparate locations, it is crucial that content filters can be deployed remotely. Options for deployment include client-side instructions for employees to install filters themselves, a remote installation by IT, or platforms that offer in-built filters.
  2. Cover the full threat spectrum: Ensure content filtering covers the entire threat spectrum. This includes protecting against credential theft, mobile malware, and virus outbreak through data loss prevention (DLP) and dynamic adult image analysis.
  3. Deploy category-based filters: Category-based filtering enables organizations to restrict access to specific categories of websites, such as adult gambling, online shopping, or social networking sites. This offers a more dynamic approach to policy implementation and more control over how users access the internet.
  4. Block specific URLs: Content filters enable organizations to exempt specific URLs from implemented rules. As a result, they allow the blocking of particular pages rather than entire websites.
  5. Implement URL filtering: URL filtering makes it easier for organizations to prevent web-based threats and monitor employee web activity without restricting user access.
  6. Implement schedule-oriented access: Employees working remotely on personal devices often need distractions after long periods of work. A schedule-oriented content filtering approach enables organizations to provide quotas of access to non-work-related websites or access to sites at specific times of the day.
  7. Use automated reporting: Organizations need to understand how effective their content filters are and the types of content that employees are accessing. Content filters increasingly offer automated reporting that provides real-time data and insight into employees' activity.

How Fortinet Can Help

Fortinet helps organizations keep their devices, users, and networks safe with its FortiGuard Web Filtering solution. FortiGuard offers advanced technologies around content security, which helps to detect and prevent rapidly evolving threats like crypto malware, ransomware, and previously unknown attack vectors.

FortiGuard provides the first line of defense against cyberattacks and blocks access to malicious websites, malware downloads, and other risky content. It secures organizations through crucial unified threat management (UTM) features that include antispam, antivirus, content filtering, and email and web filtering.

FortiGuard web filtering is available through FortiGate, Fortinet's next-generation firewall (NGFW), as well as FortiCache, FortiClient, and FortiSandbox. FortiGate contains DMZ networks that further protect networks and servers and only allow access to users that have been explicitly enabled.


What are the six types of content filters?

Content filters are used in different ways and to block access to different types of material. Common types of content filters include: Internet filters, search engine filters, DNS-based filtering, email filters, web filters, and proxy filtering.

How do I turn off content filtering?

Internet users can remove content filtering by disabling it on their router or through their search engine.

Why is content filtering important?

Content filtering prevents access to content that could pose a risk to internet users. It blocks access to content deemed illegal, inappropriate, or objectionable.