[systemd-devel] resolved vs. DNS servers listening on Linux dummy interfaces

[Petr Menšík]

Hi Peter,

is there a reason why do you want resolved to serve whole LAN? It has
its problems and I think its authors meant it as localhost cache. I
don't think resolved considers it common to have more than one DNS
server on the localhost.

Is there a reason why you wouldn't use dnsmasq, unbound or knot-resolver
instead, which are more common on routers? Do you need any
systemd-resolved specific features? Like mDNS or LLMNR resolution?

On 5/8/22 15:00, Peter Mattern wrote:
> Hello.
>
> Apparently resolved is ignoring DNS servers which are listening on
> Linux dummy interfaces.
>
> When directive "Domains" in section [Network] of the dummy interface's
> *.network unit is set as usual, "resolvectl status <dummy interface>"
> still shows "Current Scopes: none" and "resolvectl query <DNS NAME
> handled by the server>" fails.
> Seen on up to date Arch Linux with the network setup handled
> completely by networkd/resolved. As DNS servers dnsmasq and Knot were
> tested, both were working as expected on that interface type according
> to drill queries pointing to the interface's IP.
>
> Use case is a router on which I'd like to use Knot to serve a
> subdomain used in the LAN only while leaving the upstream interface to
> the ISP's DNS server and having resolved's stub resolver provide DNS
> to the LAN on the downstream interface.
> Tbh. I'm not even sure whether Linux dummy interfaces are meant for a
> purpose like this. But given that both servers (as well as nginx,
> btw.) seem to work well on the interface I'd actually expect resolved
> to pick them.
>
> So can anybody tell me what's the matter here, in particular whether
> this may be a problem of resolved or whether there's a way to get this
> working somehow?
>
> Regards
>
> Peter Mattern
>
-- 
Petr Menšík
Software Engineer
Red Hat, http://www.redhat.com/
email: pemensik at redhat.com
PGP: DFCF908DB7C87E8E529925BC4931CA5B6C9FC5CB