DNS leak while using vpn

[specter78]

Description

I have nextdns (app store app) and openvpn via Passepartout enabled at the same time.

When browsing using brave, dns requests go through nextdns (which exposes local ip) while browser ip is determined by vpn.

Steps to Reproduce

Please refer to the description above.

Actual result:

When browsing using brave, dns requests go through nextdns (which exposes local ip) while browser ip is determined by vpn.

Expected result:

Both DNS requests as well as browser traffic should go through vpn.

Reproduces how often:

Every time

Brave version (brave://version info)

Brave - 1.26.74 Chromium: 91.0.4472.124 (Official Build) (x86_64)
Revision - 7345a6d1bfcaff81162a957e9b7d52649fe2ac38-refs/branch-heads/4472_114@{6}
OS - macOS Version 11.4

Version/Channel Information:

• Can you reproduce this issue with the current release? yes
• Can you reproduce this issue with the beta channel? don't know
• Can you reproduce this issue with the nightly channel? don't know

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields? na
• Does the issue resolve itself when disabling Brave Rewards? na
• Is the issue reproducible on the latest version of Chrome? don't know

Miscellaneous Information:

If nextdns app is disabled, dns requests go though vpn, which is what should normally happen. However, in this case, page load time increases substantially.

Firefox doesn't have this issue.

[ryanbr]

Can you replicate in Chrome? @specter78

[specter78]

@ryanbr I don't use chrome.

[ryanbr]

@ryanbr I don't use chrome.

This would help debug whether its a Chromium specific issue or just Brave

[specter78]

It happens in chrome.

[ryanbr]

Okay, We'll need to log https://bugs.chromium.org/p/chromium/issues/list I don't mind helping here, I would need debug logs on what you're seeing, and step-by-step instructions to reproduce the issue @specter78

[diracdeltas]

There was a version of this that only existed in Brave, which @antonok-edm fixed in brave/brave-core#8957

[specter78]

Does Brave have CNAME uncloaking enabled? Because tabs load very slowly in normal window, but with normal performance in private window.

If CNAME uncloaking is enabled, how to disable it since NextDNS already does it.

[specter78]

@ryanbr

Here are the step-by-step instructions to reproduce the issue.

1. Install and run NextDNS app from mac app store (I'm using custom configuration)
2. Install and run vpn using Passepartout app from mac app store
3. Open ipleak.net in Brave
4. The website shows DNS close to my actual location.
5. Disable NextDNS app
6. The website shows DNS close to vpn location.
7. Also, when Passepartout is enabled and NextDNS is disabled, setting custom Secure DNS gives error "Please verify that this is a valid provider or try again later". I do not get this error when both app are enabled.

[ryanbr]

Does the same issue show up in Brave Beta @specter78 ?

[specter78]

@ryanbr Yes, both issues (slow loading in normal window and DNS leak issue) happen in brave beta also. However, neither of the issue happens in safari or firefox.

[ryanbr]

@antonok-edm This wouldn't be related to the recent CNAME issues?

[nath-old]

This is not related to the recent CNAME issues nor Brave and Chrome itself. The root cause of the DNS leak is from the Passepartout VPN client. Your system uses the nearest NextDNS server in your location rather than the nearest one on your VPN server.

I have tested this in Brave Desktop and Safari on macOS Big Sur.

EDIT: It has to do something with your OpenVPN Configuration. But still, the issue is not in any browser.

[diracdeltas]

thanks @neeythann, closing for now