Re: Changing nameservers - WAS "Which resolv.conf file?"
On Wed 31 Jul 2019 at 18:56:08 (-0400), Bob Bernstein wrote:
> I _think_ my upgrade from Jessie to Stretch -- which entailed
> installing systemd for the first time on this box -- introduced that
> 8.8.8.8. into my config. I've never been at a loss to select my own
> nameservers, and that never has been one of them.
I think there may be a path by which this¹ can happen, which imvolves
installing systemd and letting it use systemd-resolved at a time when
you have no explicit nameserver configured. This has a fallback which
you can probably still see if you haven't changed /etc/systemd/resolved.conf.
I presume that once 8.8.8.8 gets into /etc/resolv.conf, resolvconf
will hang onto it, squirrelling it away somewhere. Where? I'm not
sure, having never got into this situation, but my suspicion would
fall on /etc/resolvconf/resolv.conf.d/base (which is empty here).
(By the time my installation is done, my /etc/resolv.conf contains
192.168.1.1 and AIUI from then on, that's a permanent fallback,
being preserved in /etc/resolvconf/resolv.conf.d/original when I
install resolvconf.)
But this scenario is hypothetical, because systemd may just *use* the
compiled-in address 8.8.8.8 without storing it elsewhere at all.
> I was not even aware of that other file 'interface/' to wit:
> '/etc/resolvconf/run/interface/' or I would have been more specific
> indicating which file I edited, which was our old friend
> '/etc/network/interfaces'.
You posted in you previous thread that your /etc/network/interfaces
contained the line
dns-nameserver 8.8.8.8
and I'm not sure whether this can be explained by the above.
IOW the scenario above might explain the "8.8.8.8" leaking into *use*
in a Debian system, but I thought only the debian-installer would
write new information like "dns-nameserver" into /etc/network/interfaces
from scratch. AFAICT ifupdown only creates a file containing comments
if one doesn't already exist. So …
> QED, yes?
You didn't really prove how "8.8.8.8" arrived in your system.
¹ There was a heated discussion in #761658 about using a
Google nameserver as an unannounced default fallback.
It surprised me that systemd doesn't just use something
like the gateway address if/when some address is absolutely
essential.
Cheers,
David.
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