[Pkg-libvirt-maintainers] Problem with VMs network after upgrading to Debian 12

[Sven Geuer]

Hi gooksin,

I copy Lee Garret for being the uploader of dnsmasq-base_2.90-
4~deb12u1.

See below for my actual reply.

On Tue, 2025-01-14 at 11:46 +0100, gooksin wrote:
> Dear maintainers,
> 
> First of all, my best wishes for 2025!
> 
> I'm not sure this is the preferred  way to inform you of a problem 
> with the use of  the packages that you maintain. If  it is not so, 
> please let me know how can I send you this information.
> 
> Here is the setup that is currently having a problem:
> 
> - Debian 12.9 (upgraded on 11/01/2025 from Debian 12.8)
> - I use bind9 to serve local zones
> - I use QEMU/KVM to host two virtual machines
> - Both guest systems use NAT networking
> 
> Up to  the last upgrade (to  12.9) this setup was  working without 
> any problem. After the upgrade, whenever the virtual network would 
> start it would throw a failure error. For example, if autostarting 
> at boot:
> 
> 8<-----------------------------------------------------------------
> 
> # journalctl -b 0 -g 192.168 --no-pager
> de  gen. 12  09:45:44  XXX  systemd-networkd[512]: wlp3s0:  DHCPv4 
> address   192.168.1.67/24,  gateway   192.168.1.1  acquired   from 
> 192.168.1.1
> de gen. 12  09:45:46 XXX named[1011]: listening  on IPv4 interface 
> wlp3s0, 192.168.1.67#53
> de gen. 12  09:45:52 XXX named[1011]: listening  on IPv4 interface 
> virbr0, 192.168.122.1#53
> de gen. 12 09:45:53 XXX  dnsmasq[1243]: failed to create listening 
> socket for 192.168.122.1: Address already in use
> de  gen. 12  09:45:53  XXX libvirtd[1009]:  internal error:  Child 
> process          (VIR_BRIDGE_NAME=virbr0         /usr/sbin/dnsmasq 
> --conf-file=/var/lib/libvirt/dnsmasq/default.conf   --leasefile-ro 
> --dhcp-script=/usr/lib/libvirt/libvirt_leaseshelper)    unexpected 
> exit status 2: 
>                                           dnsmasq:    failed    to 
>                                           create  listening socket 
>                                           for       192.168.122.1: 
>                                           Address already in use
> de  gen.  12 09:45:53  XXX  named[1011]:  no longer  listening  on 
> 192.168.122.1#53
> 
> ----------------------------------------------------------------->8
> 
> If  I try  to launch  one of  the machines,  it expectedly  fails, 
> complaining that the network 'default' is not active.
> 
> After searching for help in the Debian fora, one of the moderators 
> suggested  to  downgrade  the dnsmasq-base  package.  I  therefore 
> removed and purged  dnsmasq-base_2.90-4~deb12u1 (installing during 
> the last  upgrade) and re-installed dnsmasq-base_2.89-1.  Doing so 
> "solved"  the  problem,  but  this  seems  obviously  not  a  real 
> solution.
> 
> I'm  not sure  whether  the  problem comes  from  dnsmasq or  from 
> libvirt (from which dnsmasq is launched  as a child process) nor I 
> think I would be able to  track the problem causes. I'm also sorry 
> if my wording of  the problem is not clear. Please  let me know in 
> that case and I will try to be more precise.
> 
> I therefore  request your help  to find a persistent  solution for 
> this problem.
> 
> Thanking you in advance for any help or pointers,
> 
> -- @gooksin

From your journal excerpt it is visible that named already listens on
192.168.122.1, port 53

   de gen. 12  09:45:52 XXX named[1011]: listening  on IPv4 interface virbr0, 192.168.122.1#53

then dnsmasq tries to bind to the same address and fails to do so

   de gen. 12 09:45:53 XXX  dnsmasq[1243]: failed to create listening
socket for 192.168.122.1: Address already in use

Dnsmasq up to version 2.89 accepted this type of misconfiguration.
Since 2.90 it refuses to bind to a socket already in use, what is more
correct behaviour.

Please correct named's configuration so that is does not listen on any
ip address accessible via the virbr0 interface.


Regarding:
> I'm not sure this is the preferred  way to inform you of a problem...

The probably best way is to open a bug at https://www.debian.org/Bugs/.
There is also a package "reportbug" [1] + [2] which supports you in
preparing a bug report.

Regards,
Sven

[1]
https://packages.debian.org/search?keywords=reportbug&searchon=names&suite=stable&section=all
[2] https://manpages.debian.org/bookworm/reportbug/reportbug.1.en.html

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