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Firefox leaking local data while connected to a VPN

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- I'm running Firefox ESR 52.9.0 (64-bit) in Kali Linux. - I have an IKEv2/IPsec VPN tunnel set up to a foreign VPN server with non-local-ISP DNS servers also hard coded in the resolv.conf file. - My local ISP is exercising internet censorship.

When trying to access a website that my local ISP is blocking with a browser other than Firefox, I can reach it fine. When trying via Firefox I get redirected to a page from my local ISP saying "this website is blocked blabla".

So Firefox is somehow leaking data outside of my VPN tunnel. As Firefox is my preferred browser I want to avoid having to ditch it.

Is there a setting in for instance about:config that needs adjusting?

I have been searching all over the web, but have been unsuccessful in finding the solution to this problem.

All suggestions are welcome - if more details are needed, just ask.

Thanks in advance!

- I'm running Firefox ESR 52.9.0 (64-bit) in Kali Linux. - I have an IKEv2/IPsec VPN tunnel set up to a foreign VPN server with non-local-ISP DNS servers also hard coded in the resolv.conf file. - My local ISP is exercising internet censorship. When trying to access a website that my local ISP is blocking with a browser other than Firefox, I can reach it fine. When trying via Firefox I get redirected to a page from my local ISP saying "this website is blocked blabla". So Firefox is somehow leaking data outside of my VPN tunnel. As Firefox is my preferred browser I want to avoid having to ditch it. Is there a setting in for instance about:config that needs adjusting? I have been searching all over the web, but have been unsuccessful in finding the solution to this problem. All suggestions are welcome - if more details are needed, just ask. Thanks in advance!

Chosen solution

What are your connection/proxy settings (Preferences/Advanced)?

On Windows, the default of "Use system proxy settings" piggybacks on your Windows/IE "LAN" setting. "Auto-detect" can lead to a flaky connection. You may want to try "No proxy".


If WebRTC is involved, see: https://www.reddit.com/r/firefox/comments/8hjh3h/google_voice_psa_if_you_have_been_recently_having/

Read this answer in context 👍 1

All Replies (5)

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Chosen Solution

What are your connection/proxy settings (Preferences/Advanced)?

On Windows, the default of "Use system proxy settings" piggybacks on your Windows/IE "LAN" setting. "Auto-detect" can lead to a flaky connection. You may want to try "No proxy".


If WebRTC is involved, see: https://www.reddit.com/r/firefox/comments/8hjh3h/google_voice_psa_if_you_have_been_recently_having/

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This is now working, excellent.

I already had "No proxy" set.

The setting that solved it came from the article you posted:

about:config media.peerconnection.ice.proxy_only ---> I set this to TRUE and this solved the problem.

Many thanks !!

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Not enough info given, leaving me confused on if I should be concerned.

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it's annoying, to be asked to survey BEFORE I read the webpage. Why no resize option, so I can answer the survey when I'm done?

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Hi Gnojuan, if you have a question, please feel free to post it:

https://support.mozilla.org/questions/new

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