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Prevent WebRTC from leaking local IP address

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gwarser edited this page Sep 17, 2021 · 20 revisions

Back to Dashboard: Settings

Option removed from desktop browsers in uBlock Origin v1.38.

Browsers now obfuscate LAN addresses by mDNS:

Option is still available in Android Firefox, because obfuscation is still not implemented there: "Support mDNS hostname obfuscation on Android"

Keep in mind that this feature is to prevent leakage of your non-internet-facing IP adresses. The purpose of this feature is not to hide your current internet-facing IP address -- so be cautious to not misinterpret the results of some WebRTC-local-IP-address-leakage tests found online.

Important: Enabling this feature can cause issues for some WebRTC-related services. If this is the case, you will have to disable it to prevent the breakage.

For example, if you use a VPN, your internet-facing IP address is that of the VPN, so your ISP-provided IP address should not be visible to outside world with this setting checked. However, if you are not behind any VPN or proxy, your ISP-provided IP address will be visible regardless of this setting.

Tests:

  • Trickle ICE
    • Click the Gather candidates button at the bottom; there should be no local IP addresses reported
  • WebRTC Leak Test
    • The entry "Local IP Address" should be "n/a"

Caveats

Chromium-based browsers

It has been reported that Google Hangout and Facebook messenger do not work properly when this setting is enabled (issue #757, #681).

If you are using an extension-based VPN, this setting won't prevent your ISP IP address from leaking.

Also: "When using a proxy, WebRTC leaks unproxied IP address even with multiple routes disabled" (reportedly fixed in Chromium 47, see comment #25).

The feature works only on version 42 and above.

Firefox

With Firefox 41 and lower OR uBlock Origin 1.3.3 and lower, it is NOT possible to prevent local IP addresses leakage without completely disabling WebRTC.

With Firefox 42 and higher AND uBlock Origin 1.3.4 and higher, it is possible to prevent local IP addresses leakage without completely disabling WebRTC.

Due to differences in handling of network connections by different browsers, before version 1.18.12 WebRTC was completely disabled if Firefox was not configured to use proxy. Related issue: #3009

See also

uBlock Origin - An efficient blocker for Chromium and Firefox. Fast and lean.

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