[Dnsmasq-discuss] dnsmasq: failed to create listening socket for 10.0.2.2: Address already in use

[Buck Horn]

On 11.02.25 00:17, user via Dnsmasq-discuss wrote:
> Hello,
>
> I use a Debian-based operating system called Kicksecure as a host OS, and run an operating system called Whonix inside two VMs using KVM. This setup makes use of dnsmasq. In case you are unfamiliar with Kicksecure and Whonix, here are the project pages:
>
> https://kicksecure.com
> https://whonix.org
> https://whonix.org/wiki/KVM#Start
>
> It was recent that I upgraded from the Debian 12.8 point release to Debian 12.9. When I did, I became unable to run the Whonix-Gateway VM when I click the 'Play' button in virt-manager. Here is a link to a forum user with the same problem as me: https://forums.whonix.org/t/cannot-start-whonix-external-virtual-network/21092
> This is the error I receive:
>
>
> Error starting domain: Requested operation is not valid: network 'Whonix-External' is not active
>
> Traceback (most recent call last):
>    File "/usr/share/virt-manager/virtManager/asyncjob.py", line 72, in cb_wrapper
>      callback(asyncjob, *args, **kwargs)
>    File "/usr/share/virt-manager/virtManager/asyncjob.py", line 108, in tmpcb
>      callback(*args, **kwargs)
>    File "/usr/share/virt-manager/virtManager/object/libvirtobject.py", line 57, in newfn
>      ret = fn(self, *args, **kwargs)
>            ^^^^^^^^^^^^^^^^^^^^^^^^^
>    File "/usr/share/virt-manager/virtManager/object/domain.py", line 1402, in startup
>      self._backend.create()
>    File "/usr/lib/python3/dist-packages/libvirt.py", line 1373, in create
>      raise libvirtError('virDomainCreate() failed')
> libvirt.libvirtError: Requested operation is not valid: network 'Whonix-External' is not active
>
>
> When I tried the command
>
> 	virsh -c qemu:///system net-start Whonix-External
>
> to start the VM, I receive this error involving dnsmasq:
>
> 	error: Failed to start network Whonix-External
> 	error: internal error: Child process (VIR_BRIDGE_NAME=virbr1 /usr/sbin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/Whonix-External.conf --leasefile-ro --dhcp-script=/usr/lib/libvirt/libvirt_leaseshelper) unexpected exit status 2:
> 	dnsmasq: failed to create listening socket for 10.0.2.2: Address already in use
>
> I used this command, but I do not see any mention of 10.0.2.2 at all:
>
> 	ss -l -p


This seems similar to
  https://bugs.launchpad.net/ubuntu/+source/dnsmasq/+bug/2055776
where the verdict was:

 > Two different services attempting to bind on a single (IP, port)
tuple is going to lead to a failure of one of the services. Prior to
this update it was a silent failure, which serves only to make debugging
problems more difficult.


To be able to avoid such a conflict, you'd first need to find out what's
claiming port 53.

What's the output of:

sudo ss -tulpn sport = 53


Kind regards,
       Buck