Question How do you disable DoH in Firefox?

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rashmi

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I thought of trying Firefox, but there is no option to disable DoH in Firefox. You can disable DoH in Chrome and Edge, but Firefox DOH (OFF) says "Use your default DNS." Chrome and Edge with DoH disabled don't leak DNS when I use VPN, but Firefox leaks DNS with DoH default and OFF.
 
You can disable DoH in Firefox. Go to Options > General > Network Settings > Settings, then under "Enable DNS over HTTPS", select "Off". If you're still experiencing DNS leaks, it might be an issue with your VPN configuration rather than Firefox itself.
 
rashmi said:
I thought of trying Firefox, but there is no option to disable DoH in Firefox. You can disable DoH in Chrome and Edge, but Firefox DOH (OFF) says "Use your default DNS." Chrome and Edge with DoH disabled don't leak DNS when I use VPN, but Firefox leaks DNS with DoH default and OFF.
Click to expand...
Sounds the issue for you is the DNS leak in Firefox while using VPN?

Just check for Firefox settings related to WebRTC:
Use these instructions if you wish to manually disable WebRTC:
  1. Type "about:config" into the address bar and hit Enter.
  2. Click the button "I accept the risk!".
  3. Type media.peerconnection.enabled in the search bar. Only one entry should appear.
  4. Double-click on the entry to change it to false.
To enable WebRTC again, change it back to "true".
Click to expand...
mullvad.net

WebRTC

Learn about what WebRTC is and how to keep it from exposing your IP.
mullvad.net mullvad.net
 
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People have also reported a DNS leak issue here.
connect.mozilla.org

Firefox has DNS leak security issue

When I was using a proxy to surf the Internet, to ensure my security, I checked the DNS leak status. When I use Firefox, the query results show that my DNS is leaked and the DNS is my real DNS. However, when I use Chrome to query, there is no DNS leak. This is a serious security issue. Please...
connect.mozilla.org connect.mozilla.org
 
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To disable DoH in Firefox, follow these steps:
  1. Open Firefox: Open the Firefox browser on your device.
  2. Click the menu button: Click the three horizontal lines () at the top right corner of the browser window.
  3. Select Options: Click on “Options” from the drop-down menu.
  4. Go to Network Settings: In the Options window, click on the “Network Settings” tab.
  5. Scroll down to Enable DNS over HTTPS: Scroll down to the “Enable DNS over HTTPS” option.
  6. Uncheck the box: Uncheck the box next to “Enable DNS over HTTPS” to disable DoH.
  7. Click OK: Click the “OK” button to save your changes.
Alternatively, you can also disable DoH by using the about:config page:

  1. Type about:config in the address bar: Type “about:config” in the address bar and press Enter.
  2. Search for network.dns.disablePrefetch: Search for the “network.dns.disablePrefetch” preference.
  3. Double-click to toggle: Double-click on the preference to toggle it to “true”.
Note: Disabling DoH may affect the performance and security of your internet connection. It is recommended to only disable DoH if you have a specific reason to do so, such as using a custom DNS server or experiencing issues with DoH.
 
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Ah! Go type this into your Firefox address bar:
Code: 
about:config
Then search for network.trr.mode and set the value to 5. Here is a Firefox document explaining the settings.

Here is a useful Firefox document of other parameters that you might want to check also:

trr.png


Then check what resolvers your Firefox browser is using via this useful website:

dnscheck.tools - check your dns resolvers

A tool to test for DNS leaks, DNSSEC validation, and more
www.dnscheck.tools www.dnscheck.tools
 
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Spiff said:
Ah, thanks very much.
So, two AI said similar things regarding Firefox DNS over HTTPS settings, not matching what is in the Mozilla Support article.
It seems that somehow both MalwareTips Bot and Brave AI based their responses on outdated documentation.
Click to expand...
I noticed that after I read your comment, I think I should check after AI answers, it is why I don't like AI.
 
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rashmi said:
I used ipleak.net and browserleaks.com. Both websites show DNS leaks.
Click to expand...

I just tried both and they show no leaks. All I did was follow the media.peerconnection.enabled setting.

You can probably install the Mullvad browser and Firefox Portable in the same machine and test those, too.
 
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monkeylove said:
I just tried both and they show no leaks. All I did was follow the media.peerconnection.enabled setting.

You can probably install the Mullvad browser and Firefox Portable in the same machine and test those, too.
Click to expand...
I already have the media.peerconnection.enabled policy set to false. I tried Firefox Portable, and the test websites showed DNS leaks.
 
monkeylove said:
You can probably bring a laptop to a place that uses another ISP and see what happens.
Click to expand...
I tried my mobile's hotspot, which is a different ISP, and the outcome was the same. With DoH disabled, Chrome and Edge didn't leak DNS, but Firefox did.
 

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