Enabling DNS over HTTPS (DoH) in Firefox: A Comprehensive Guide

DNS over HTTPS (DoH) is a privacy-enhancing technology that encrypts your DNS queries, preventing your internet service provider (ISP) and potential eavesdroppers from seeing which websites you visit. This guide provides a step-by-step walkthrough on how to enable DoH in Mozilla Firefox, along with explanations of the benefits, considerations, and troubleshooting steps.

Understanding DNS over HTTPS

Traditionally, DNS lookups (translating domain names like google.com into IP addresses) are sent in plain text. This means anyone monitoring your network traffic can see every website you access. DoH encrypts these queries using HTTPS, the same protocol used for secure websites. This added layer of security protects your privacy and prevents potential manipulation of your DNS results through techniques like DNS spoofing.

Enabling DoH in Firefox: The Easy Way (Recommended)

Firefox offers a simple built-in method to enable DoH. This is the recommended approach for most users due to its ease of use and automatic updates:

Open Firefox Preferences: Click the three horizontal lines (menu button) in the upper right corner of the browser window, and select "Settings" (or "Preferences" on macOS).
Navigate to Privacy & Security: In the left-hand sidebar, click on "Privacy & Security."
Find Network Settings: Scroll down to the "Network Settings" section.
Enable DNS over HTTPS: Locate the "DNS over HTTPS" setting. You should see a dropdown menu. Select your preferred provider (Firefox usually suggests Cloudflare, Google, or Mozilla's own service). If you prefer to use a custom provider, select 'Custom' and enter the address manually in the field provided.
Restart Firefox: After selecting your DoH provider, restart your Firefox browser for the changes to take effect.

Choosing a DNS over HTTPS Provider

Several reputable providers offer DoH services. Popular options include:

Cloudflare (1.1.1.1): Known for its speed and privacy focus.
Google Public DNS: Widely used and well-established.
Mozilla: Offers a privacy-respecting option managed by the Firefox developers.
Quad9: Focuses on security and blocking malicious websites.

The best provider for you depends on your priorities. Consider factors like speed, privacy policies, and security features when making your selection.

Manual Configuration (Advanced Users)

For advanced users, it's possible to manually configure DoH using Firefox's about:config settings. However, this method is generally not necessary and carries a higher risk of misconfiguration. Only proceed with this method if you are comfortable editing advanced settings and understand the potential consequences.

Type about:config in the Firefox address bar and press Enter.
Accept the warning message.
Search for network.trr.mode. Double-click to change its value to 2 (to enable DoH). Alternatively, search for network.trr.uri to specify a custom DoH endpoint. The format for the uri is usually like https://[server address]/dns-query, replacing the bracketed part with your chosen server address (e.g., https://cloudflare-dns.com/dns-query).
Restart Firefox.

Modifying about:config incorrectly can negatively impact your browser's functionality. Exercise caution and ensure you understand the changes you are making.

Troubleshooting

If DoH doesn't seem to be working, try the following:

Restart your computer and router: Sometimes a simple reboot resolves network issues.
Check your network configuration: Ensure your network settings are correctly configured and your internet connection is stable.
Verify your DoH provider: Make sure the address you entered is accurate.
Disable other extensions or add-ons: Some extensions might interfere with DoH functionality.

Conclusion

Enabling DNS over HTTPS in Firefox significantly enhances your online privacy. By following the steps in this guide, you can easily protect your DNS queries from unwanted observation. Remember to choose a reputable DoH provider that aligns with your privacy preferences.