[libvirt-users] libvirt and NAT on a system that already has a DHCP server

[Laine Stump]

On 02/01/2018 09:22 AM, Daniel P. Berrangé wrote:
> On Thu, Feb 01, 2018 at 09:19:11AM -0500, Laine Stump wrote:
>> On 01/30/2018 07:37 PM, john at bluemarble.net wrote:
>>> I'm trying to use virt-manager and qemu/kvm on Arch Linux. The box I'm
>>> using is also the router for my house. It runs a kea DHCP server. When I
>>> try to start the default NAT network, it can't start dnsmasq because that
>>> port is already bound. Is there a way to have it not bind on this
>>> interface? I see there is an except-on statement in the dnsmasq.conf, but
>>> I can't add lines to that directly, and I didn't see any way to add
>>> special options using virsh net-edit default.
>>
>> The dnsmasq processes run by libvirt to serve dhcp for the virtual
>> networks already does this - they listen *only* on the bridge created
>> for their particular network, nothing else. Your problem is that your
>> host system's dhcp server has been configured to automatically listen on
>> all interfaces.
>>
>> So it's not the configuration of the libvirt network that needs to
>> change, it's the configuration of the host system's dhcp server. It
>> needs to be told that it shouldn't automatically listen on all new
>> interfaces, but to just listen on certain specific interfaces.
> 
> Checkout this
> 
> https://wiki.libvirt.org/page/Libvirtd_and_dnsmasq


Useful for dnsmasq, but he says his host is using "kea dhcp server",
which appears to be some off-shoot of ISC dhcpd, so the config would be
different.