Closed Bug 1630276 Opened 6 years ago Closed 6 years ago

Domains are not resolving through DoH when connected to VPN server

Categories

(Core :: Networking: DNS, defect)

Product:
Core
Component:
Networking: DNS
Version:
75 Branch
Type:
defect
Priority:
Not set
Severity:
normal

Tracking

()

Status:
RESOLVED INVALID

People

(Reporter: pirpiliter, Unassigned)

Details

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:75.0) Gecko/20100101 Firefox/75.0

Steps to reproduce:

Set DoH from Cloudflare on in Firefox (or any other DoH server at which you have access to watch logs)

Open https://1.1.1.1/help , you will see "Using DNS over HTTPS (DoH) Yes"

Connect to a VPN server (any protocol except OpenVPN); with DoH from Cloudflare turned on

Open again https://1.1.1.1/help in a new tab, you will see: "Using DNS over HTTPS (DoH) No"

Actual results:

Domains did not resolve through DoH server set up in Firefox but with DNS servers from your VPN connection

Expected results:

Domains should have been resolved with DoH server from Cloudflare

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

Component: Untriaged → Networking: DNS
Product: Firefox → Core

Can you look at about:networking#dns and see if Trr column is "true"? If so then Firefox is using DoH.

Flags: needinfo?(pirpiliter)

When not connected to VPN domains are true, when connected to VPN all new domains are false

Flags: needinfo?(pirpiliter)

Valentin, is this expected when using a VPN? Thanks.

Flags: needinfo?(valentin.gosu)

On Windows, likely yes.
So we have this feature that disables DoH when a VPN is active in order to avoid split-horizon DNS issues.
pirpiliter: can you check if this still happens for you if you change the network.trr.enable_when_vpn_detected pref to true in about:config ?

Thanks!

Flags: needinfo?(valentin.gosu) → needinfo?(pirpiliter)

(In reply to Valentin Gosu [:valentin] (he/him) from comment #5)

On Windows, likely yes.
So we have this feature that disables DoH when a VPN is active in order to avoid split-horizon DNS issues.
pirpiliter: can you check if this still happens for you if you change the network.trr.enable_when_vpn_detected pref to true in about:config ?

Thanks!

It works.

"Disabling DoH when VPN connected" was added in the recent version of Firefox right?

Flags: needinfo?(pirpiliter)

(In reply to pirpiliter from comment #6)

(In reply to Valentin Gosu [:valentin] (he/him) from comment #5)

On Windows, likely yes.
So we have this feature that disables DoH when a VPN is active in order to avoid split-horizon DNS issues.
pirpiliter: can you check if this still happens for you if you change the network.trr.enable_when_vpn_detected pref to true in about:config ?

Thanks!

It works.
Domains are resolved trough DoH when network.trr.enable_when_vpn_detected is true

Thanks for confirming. That's good to know. Maybe we'll reconsider how we disable this in the presence of a VPN at some point in the future, but right now it just means the feature works 🙂

Status: UNCONFIRMED → RESOLVED
Closed: 6 years ago
Resolution: --- → INVALID
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