Brave is leaking public IP address through WebRTC when using proxy

[derzahla]

Description

Brave is leaking public IP address through webRTC while using a VPN through a proxy. Similar as reported and fixed here: #9041

Steps to Reprod

1. Set proxy using a basic extension sets a proxy via local PAC file
2. Browse to https://browserleaks.com/webrtc
3. True public IP address is shown rather than the public IP address of the proxy being used

Actual result:

Expected result:

Public IP address detected should be that of the proxy server. Brave should either route all WebRTC traffic through the proxy or should not send it at all

Reproduces how often:

Every time when using a proxy

Brave version (brave://version info)

Brave	1.38.84 Chromium: 100.0.4896.79 (Official Build) dev (64-bit)
Revision	8fb749dcab8700c24213791969e59deb72fee36f-refs/branch-heads/4896@{#1015}
OS	Linux

Version/Channel Information:

Untested

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields? Yes
• Does the issue resolve itself when disabling Brave Rewards? Yes
• Is the issue reproducible on the latest version of Chrome? Yes

Miscellaneous Information:

[madhatr]

I'm using IPA extension as VPN and my actual public IP shows up on that webRTC test page.

[NumDeP]

@derzahla when you say VPN through a proxy, do you also mean via an extension like @madhatr or is it a desktop/standalone application?

Have either of you set your WebRTC policy in Settings to Disabled non-proxied UDP? It's suppose to fix issues like this if I remember.

[madhatr]

@NumDeP Thank you, that setting fixed my IP leak with the IPA extension.

[derzahla]

@NumDeP Sorry for the late response. Yes, I have a basic local extension template incorporated my proxy pac file. That setting seems to work, thank you, I must have missed it. Perhaps disabled by default would be the best config for brave though.