NetworkManager does not use openconnect GlobalProtect VPN's DNS

[Fikrul Arif]

1. Add a GlobalProtect VPN in network settings GUI, set DNS to manual, enter DNS IP address.
2. Open an internal website that should be routed through the VPN.

Actual: failed to open the internal website.
Expected: should open the internal website.

Content of `/etc/resolv.conf`: using systemd-resolved's 127.0.0.53.

Output of `resolvectl status`: only wlo1 has DNS Servers entry, there is no DNS Servers entry in vpn0.

Workaround: manually set the DNS in /etc/resolv.conf. Side effects of the workaround: the setting does not persist.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: openconnect 8.05-1
ProcVersionSignature: Ubuntu 5.8.0-59.66~20.04.1-generic 5.8.18
Uname: Linux 5.8.0-59-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu27.18
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Thu Jul 8 13:35:21 2021
InstallationDate: Installed on 2021-06-05 (33 days ago)
InstallationMedia: Ubuntu 20.04.2.0 LTS "Focal Fossa" - Release amd64 (20210209.1)
SourcePackage: openconnect
UpgradeStatus: No upgrade log present (probably fresh install)

[dwmw2 (dwmw2)]

What does "nmcli con show" say for the offending connection? Does NM know the DNS server? Is this just a case of Ubuntu's NM not working correctly with its systemd DNS setup?

If you connect with openconnect on the command line and add the `-v` option, do you see DNS servers? I have a feeling Ubuntu's vpnc-script may not be working correctly for DNS either, so I'm less interested in whether it *works* and asking for the debug output.

[Fikrul Arif (fikr4n)]

> What does "nmcli con show" say for the offending connection?

```
$ nmcli con show
NAME UUID TYPE DEVICE
The VPN Name xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx vpn wlo1
The WiFi Name xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx wifi wlo1
vpn0 xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx tun vpn0
virbr0 xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx bridge virbr0
Other WiFi xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx wifi --
```

> Does NM know the DNS server?
Not sure, but I've set it manually via the GUI the make sure of it.

> If you connect with openconnect on the command line and add the `-v` option, do you see DNS servers?
I can't see such "DNS" or "name server" in the output. Btw, if I connect by executing the command line, there's no DNS problem, because it hardcodes `/etc/resolv.conf` to the VPN's DNS, the default 127.0.0.53 is deleted, replaced by 10.x.x.x.