DNS Leak on Windows 10

[sinclair8228]

Describe the bug
I am running ocserv on my VPN server. When I use OpenConnect GUI on my Windows 10 client, it does not change the DNS settings and I am still using my ISP dns resolvers. IP address does change. This problem does not occur on my Linux laptop. I am using Unbound on the server to resolve all DNS, including for OpenVPN, for which this does work. Ocserv is set to use 127.0.0.1 as dns, Unbound set to listen at 127.0.0.1 and access-control also allows.

To Reproduce
Steps to reproduce the behavior:
Login to server via username and password.

Expected behavior
DNS resolved by Unbound

Screenshots
Unable to provide at this time, away from Windows computer. Can provide later upon request

Desktop (please complete the following information):

• OS: Windows 10
• Browser Firefox, Brave, Chrome
  -All latest versions

[horar]

So, as I understood the problem doesn't appears when you use OpenConnect-GUI on linux, just the windows version raise the problem?

[sinclair8228]

Acutally, I use the command line to connect on Linux. A script executed by a .desktop file. This is my first attempt using the OpenConnect GUI, so as of now is strictly a Windows (10) problem. Dns is routed through the tunnel correctly with my Linux setup

[horar]

Could you please try command line tool on windows as well? (it's an optional part of windows installer). Thanks.
Other point would be to change 'REDIRECT_GATEWAY_METHOD' variable in vpnc script (in the same folder asd GUI is installed)... Thanks.

[odkrys]

Unfortunately, this is normal behavior in windows 10.
I can't find solution for other than Openvpn's block-outside-dns.
https://github.com/OpenVPN/openvpn/search?q=block-dns-outside&type=Commits

[horar]

@odkrys did you tri to change refered variable in vpnc script?

[odkrys]

if (env("REDIRECT_GATEWAY_METHOD")) {
	var REDIRECT_GATEWAY_METHOD = env("REDIRECT_GATEWAY_METHOD");
} else {
	var REDIRECT_GATEWAY_METHOD = -1;
}

I tried -1 to 2 but no luck.

[horar]

Then it look like the problem should be discussed on openconnect mailing list. This project is about GUI only...