VPN and Firefox ip leak potential

Sicko65 · June 20, 2020

So I recently discovered the hard way that Firefox enabled DNS over https which caused ip leaks. Not sure if this is a common issue or if it's been posted before but the fix is to go to preferences >network settings>DNS over https and disable it. Hope this helps someone avoid frustration because I thought I messed up in the order I turn my VPN to play games.

mtz_federico · June 21, 2020

dns over https doesn't cause ip leaks

Sicko65 · June 24, 2020

What is a "WebRTC leaks"?

WebRTC implement STUN (Session Traversal Utilities for Nat), a protocol that allows to discover the public IP address. To disable it:

Mozilla Firefox: Type "about:config” in the address bar. Scroll down to “media.peerconnection.enabled”, double click to set it to false.
Google Chrome: Install Google official extension WebRTC Network Limiter.
Opera: Type "about:config" in the address bar or go to "Settings". Select "Show advanced settings" and click on "Privacy & security". At "WebRTC" mark select "Disable non-proxied UDP".

What is a "DNS leaks"?

In this context, with "DNS leak" we mean an unencrypted DNS query sent by your system OUTSIDE the established VPN tunnel.

Why my system suffers DNS leaks?

In brief: Windows lacks the concept of global DNS. Each network interface can have its own DNS. Under various circumstances, the system process svchost.exe will send out DNS queries without respecting the routing table and the default gateway of the VPN tunnel, causing the leak.

Should I be worried for a DNS leak?

If you don't want that your ISP, and anybody with the ability to monitor your line, knows the names your system tries to resolve (so the web sites you visit etc.) you must prevent your system to leak DNS. If you feel that you're living in a human rights hostile country, or in any way the above mentioned knowledge may harm you, you should act immediately to stop DNS leaks.

WereCatf · June 24, 2020

10 minutes ago, Sicko65 said:

What is a "WebRTC leaks"?

WebRTC has nothing to do with DNS.

10 minutes ago, Sicko65 said:

What is a "DNS leaks"?

In this context, with "DNS leak" we mean an unencrypted DNS query sent by your system OUTSIDE the established VPN tunnel

DNS-over-HTTPS isn't unencrypted and it isn't being sent outside of the VPN-tunnel, unless your tunnel itself is misconfigured.