openvpn dns issue

[Colin Law]

On 7 December 2016 at 16:51, Colin Law <clanlaw at gmail.com> wrote:
> I wonder whether anyone can help with this rather odd problem.

Ah, got it.

https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/1644098

Colin

>
> I am using Ubuntu 16.10 with Unity Desktop.  I have vpn access to two
> servers running openvpn, one a Pi running raspbian Jessie and the
> other another Ubuntu Desktop running 14.04. I can connect to either of
> the remote systems via the vpn and everything seems to be working
> fine.  The problem arises when I disconnect  from the vpn and later
> reconnect, I then find that I have no DNS available. Internet access
> via IP is ok, it is just DNS that is not working. For example, dig
> www.google.com just times out.
>
> In the vpn servers I have specified
> push "redirect-gateway def1 bypass-dhcp"
> which I believe should send dns requests through the server, and using
> tcpdump I can see that this is the case, dns requests are sent via
> tun0.  However when I disconnect and reconnect I no longer see the
> requests on tun0, but on eth0.  In order to recover I have to reboot
> the PC (the client, I do not need to touch the servers) and then the
> first time I connect all is well again.
>
> It is not even necessary to reconnect to the same server to see the
> problem, if I connect to server A, then disconnect and connect to
> server B then again I see the dns problem
>
> I can't see anything obvious in the logs and I have not managed to get
> any clues via google.  Can anyone suggest what I might do to analyse
> this?
>
> Colin