So here is my plan.
Over the next few days I plan to use one or more VMs to test various
configurations using systemd-resolved to see which ones work and which do not.
Then we should be
able to track down why.
Do you have any suggestions?
Thanks.
--
*********************************************************
David P. Both, RHCE
He/Him/His
*********************************************************
www.both.org - My personal web site
www.Linux-Databook.info - Home of the DataBook for Linux
DataBook is a Registered Trademark of David Both
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The value of any software lies in its usefulness
not in its price.
— Linus Torvalds
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On Thu, 18 Feb 2021, Michael Catanzaro wrote:
Date: Thu, 18 Feb 2021 10:46:53
From: Michael Catanzaro <mcatanz...@gnome.org>
Reply-To: Development discussions related to Fedora
<devel@lists.fedoraproject.org>
To: David Both <da...@both.org>
Cc: Development discussions related to Fedora <devel@lists.fedoraproject.org>,
Steve Dickson <ste...@redhat.com>
Subject: Re: Don't update to the latest f33!
On Thu, Feb 18, 2021 at 10:39 am, David Both <linuxgee...@both.org> wrote:
Ok, so I manage my network using DHCP on an internal server for all except
that server and my Linux firewall/router which both use a complete static
configuration for networking.
My DHCP server does provide DNS resolver information which, in order, is
my internal BIND server (same physical server host), 8.8.8.8, and 8.8.4.4.
But my hosts were not getting that information. I think the difference
between the working and failing hosts is possibly (experiments required)
left-over ifcfg files some of which specified DHCP but also name servers
while others specified DHCP but did not specify name servers, as well as
some newer hosts that do not have any ifcfg files. I have also noticed
that ifcfg files are no longer created automatically but work when
created. I missed that information also.
OK, so DHCP is not working somehow. Are you running NetworkManager? That is
my #1 guess right now, because without NetworkManager, you have no easy way
to get DNS configuration from DHCP to systemd-resolved. systemd-resolved
doesn't configure itself: that's the responsibility of a higher-level
management layer, usually NetworkManager, or alternatively systemd-networkd.
You can configure it manually with your own scripts if you're really
hardcore. But if you have disabled NetworkManager, then my recommendation
would be to disable systemd-resolved as well. If you *are* running
NetworkManager, then unfortunately we're probably going to need to debug
NetworkManager to figure out why the configuration from DHCP is getting
dropped. I don't know how to help with that, but that also seems unlikely
because nobody has reported bugs related to that as far as I know.
If you are running NetworkManager, here are some more general troubleshooting
steps that I had typed up to send before reading the above:
The most important thing to do is to check the output of 'resolvectl' and
look for anything suspicious. Ideally the DNS server you want things going to
will be listed under each desired network interface with +DefaultRoute set.
Hopefully something will be obviously wrong there, but if not, you can post
the output of 'resolvectl' here for us to take a look.
To ensure systemd-resolved's configuration doesn't get bypassed, you'll also
want to ensure you're running Fedora's new default configuration, which you
should be, since users should be automatically upgraded. But just in case,
it's good to check:
* Ensure NetworkManager is running ('systemctl status
NetworkManager.service'). If not, you're on your own and should consider
disabling systemd-resolved since it's not worth trying to use manually.
* Ensure systemd-resolved is running: 'systemctl status
systemd-resolved.service'
* Ensure /etc/resolv.conf is symlinked to
/run/systemd/resolve/stub-resolv.conf (this ensures anything reading it
manually gets pointed to systemd-resolved's IP address, 127.0.0.53)
* Ensure the hosts line in /etc/nsswitch.conf looks like this: files
mdns4_minimal [NOTFOUND=return] resolve [!UNAVAIL=return] myhostname dns
(Remember to never edit /etc/nsswitch.conf manually, instead edit
/etc/authselect/user-nsswitch.conf and then run 'sudo authselect
apply-changes'.)
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