[Dnsmasq-discuss] Possible to reuse Cache over restarts?

[Geert Stappers]

On Thu, Jun 30, 2022 at 08:01:36PM +0200, Petr Menšík wrote:
> On 30. 06. 22 14:32, Tobias Hochgürtel wrote:
> > Geert Stappers wrote:
> >   * Tell us which version of dnsmasq is being used
> >   * Reread the manual page and in particular --log-queries option
> > 
> > [root at router-fedora ~]# *hostnamectl*
> > Static hostname: router-fedora
> >        Icon name: computer-desktop
> >          Chassis: desktop 🖥
> >       Machine ID: c9c0e33265b848bfbce224fd8615fb30
> >          Boot ID: 0824361c352745c0a35a75167a2f81a0
> > Operating System: *Fedora Linux 36 (Server Edition)*
> >      CPE OS Name: cpe:/o:fedoraproject:fedora:36
> >           Kernel: *Linux 5.18.6-200.fc36.x86_64*
> >     Architecture: x86-64
> > Hardware Vendor: BIOSTAR Group
> >   Hardware Model: N3150NH
> > 
> > [root at router-fedora ~]# *dnsmasq --version*
> > *Dnsmasq version 2.86*Copyright (c) 2000-2021 Simon Kelley
> > Compile time options: *IPv6 GNU-getopt DBus no-UBus no-i18n IDN2 DHCP
> > DHCPv6 no-Lua TFTP conntrack ipset auth cryptohash DNSSEC loop-detect
> > inotify dumpfile*
> > 
> > This software comes with ABSOLUTELY NO WARRANTY.
> > Dnsmasq is free software, and you are welcome to redistribute it
> > under the terms of the GNU General Public License, version 2 or 3.
> 
> I am maintainer of Fedora dnsmasq package.  I don't know about any issue
> with latest dnsmasq on f36. It should work reliably.
> 
> I agree with Geert, log-queries option should reveal the most details for
> troubleshooting. Default logging to journal should be enough. Use
> "journalctl -xeu dnsmasq" command to see the most recent output of dnsmasq.
> 
> You should see whether incoming query were received by the dnsmasq. And
> where did it forwarded it. It should log also what forwarder replied. If
> reply after forward is not logged but wireshark can record such packets, it
> would mean some error in socket handling code. But I think all known errors
> in Fedora 36 were fixed.
> 
> It is possible to send SIGHUP to dnsmasq to clear just cache. Just use kill
> -SIGHUP $(pidof dnsmasq). But that should not be necessary, especially not
> periodic way. Because systemd-resolved is enabled by default on Fedora, are
> you sure you have disabled it correctly? Are you connected by multiple
> interfaces at the same time? Would it work with just one interface
> connected?
> 
> Lets find somehow a reason for your broken resolution instead of dumping the
> cache periodically. While it should work even with that, it definitely
> should not be required.

I also would like to know what is causing the need for restarting dnsmasq.
 

> Cheers,
> Petr