[Bug 1971535] Re: systemd-resolved doesn't work properly for VPN connection

[Nick Rosbrook]

I think ideally your VPN would configure this DNS server as one of
systemd-resolved's upstream servers, so that using the stub resolver
would work as expected. For example, I think the following would also
work:

$ resolvectl dns <iface> 10.65.206.2

That tells systemd-resolved to use 10.65.206.2 as an upstream DNS server
for the specified interface.

** Changed in: systemd (Ubuntu)
       Status: New => Incomplete

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Title:
  systemd-resolved doesn't work properly for VPN connection

Status in systemd package in Ubuntu:
  Incomplete

Bug description:
  I'm using network-manager-openconnect-gnome (Cisco AnyConnect with certificate authentication).
  When VPN connection is established local addresses cannot be resolved by systemd-resolved.
  Content of /etc/resolv.conf:
     nameserver 127.0.0.53
     options edns0 trust-ad
     search 10.65.206.5

  Content of /run/systemd/resolve/stub-resolv.conf:
     nameserver 127.0.0.53
     options edns0 trust-ad
     search 10.65.206.5

  Content of /run/systemd/resolve/resolv.conf:
     nameserver 10.65.206.5
     search 10.65.206.5

  If I change nameserver to 10.65.206.5 in /etc/resolv.conf local
  addresses resolv works OK!

  Output of dnstracer is in attached file: dnstracer_v_vs.txt.

  If I set DNS server address to 10.65.206.2 everything work OK, output
  of dnstracer with server specified is in attached file:
  dnstracer_v_vs.txt.

  For previous LTS it's working without problems.
  Clean install of Ubuntu 20.04.4 LTS - no problem.
  Clean install of Ubuntu 22.04 LTS - resolv problem.

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