lost connection on dynamic IP

[Vicente Bergas]

Hello Roman,

On Wed, May 19, 2021 at 8:43 PM Roman Mamedov <rm at romanrm.net> wrote:
>
> On Tue, 18 May 2021 13:22:31 +0200
> Vicente Bergas <vicencb at gmail.com> wrote:
>
> > A server connected to the Internet through an ISP that provides a
> > dynamic IP with NAT.
>
> If it's NAT, then your server has no dedicated public IP? What do you update
> to DNS, IP of the ISP's NAT pool (shared IP with many other customers)?

There is a public IP assigned to the router. The IP is dynamic, so, it
can change from time to time, but, once assigned, it is exclusive to
the router.
There is no carrier-grade NAT.
I've configured the router to forward the wireguard port to the
server, so, it is like the server is directly connected to the
Internet.
I think the PersistentKeepalive on the server side is not required. Is it?

On the client side, instead, the router has no port forwarded and
also, i think, there is CGNAT. That is the reason PersistentKeepalive
is present.

> > I think the issue happens when the ISP on the server side shuts down
> > the Internet connection for more than 1 hour! Then, it is restored
> > with a new IP.
> > inadyn detects the new IP and updates the DNS.
> > At this point the Internet connection is operational again, but the
> > client remains disconnected until rebooted.
> >
> > Is this scenario expected to work due to the "Built-in Roaming" ?
>
> It might work, helped by PersistentKeepalive, and as long as the server and the
> client don't change their IPs/ports *at the same time*. To protect against
> that, or to improve resiliency in general (and assuming there's actually no NAT
> at the server side after all), your client should resolve the DNS record for
> the server periodically, and in case the IP changed, call "wg set [interface]
> peer [key] endpoint [IP:port]".

So, what do you mean is that wireguard does a single DNS resolution at
the beginning and further DNS resolutions need to be done elsewere. Is
that correct?

> With respect,
> Roman

Regards,
  Vicenç.