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

[John Ratliff]

On 2/1/2018 9:28 AM, Laine Stump wrote:
> 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.
> 

Thanks. I asked on the kea list and they say they don't have a method to 
do this. Something about raw packets. I may try to switch to dnsmasq for 
my DHCP server on the machine. For now, I'm back to VirtualBox.

Thanks.