ANSWERED DNS Leak on VM Guest

[Knechtj 0]

I've connected to an AirVPN wireguard server on my host computer. I'm using wireguard configuration files and connecting through the command line on the host (wg-quick). I'm using VirtualBox with a NAT network; VirtualCable is selected.

On the host, ipleak.net doesn't reveal any DNS leaks (Mullvad, Brave, chromium)

On the guest, ipleak.net indicates a DNS leak, on all browsers I've tried (Mullvad, Brave, chromium). This is while the host wireguard connection is established on the host, which has already indicated no DNS leaks (on the host computer). Yes-- the guest browser indicates a leak through the host wireguard network even when the guest shows a correct public wireguard ip.

Any ideas what in the world could be going on? I'm starting to wonder if this is an issue with VirtualBox networking or a bug with wireguard itself....

Edited ... by Knechtj

[Tech Jedi Alex 1583]

On the guest the DNS servers are not touched, so whatever is configured there is used over the VPN line – or completely outside of it, in case your router (= the default gateway of the host) is the DNS server.

Also maybe interesting to mention that whatever DNS is configured on the host at VM start is passed to the VM, if I'm understanding the docs right. So maybe connect Wireguard first, then start the VM to ensure the correct DNS servers are passed to the VM.

Also, while we're at it, beware of testing with browsers: Some have "Secure DNS" or similar enabled, which means DoH/DoT and similar, completely bypassing your configured DNS servers. Test DNS with dig or nslookup which print the DNS server they used.

[Knechtj 0]

This was quite helpful. It does seem this DNS behavior is from changing the wireguard connection *after* starting the VM. When the initial wireguard connection is untouched, there is on DNS issue on the guest. Thank you!!!