Libvirt Networking – Set Default Gateway for Guest VMs via DHCP

dhcplibvirt

Is it possible to set a default gateway for the guest VMs via DHCP in libvirt?

I have the following config

<ip address='192.168.123.1' netmask='255.255.255.0'>
  <dhcp>
    <range start='192.168.123.10' end='192.168.123.254'/>
    <host mac="00:16:3e:45:e2:ed" ip="192.168.123.10"/>
    <host mac="00:16:3e:53:a9:1a" ip="192.168.123.11"/>
    ...
  </dhcp>
</ip>

and now it would be nice to somehow add a **gateway** to the guest VMs like that:

<ip address='192.168.123.1' netmask='255.255.255.0'>
  <dhcp>
    <range start='192.168.123.10' end='192.168.123.254'/>
    <host mac="00:16:3e:45:e2:ed" ip="192.168.123.10" **gateway=192.168.123.1**/>
    <host mac="00:16:3e:53:a9:1a" ip="192.168.123.11" **gateway=192.168.123.1**/>
    ...
  </dhcp>
</ip>

How can I do that? I have only found
this source, saying that it is not possible. However, this is from 2016. Has anything changed yet or is there another solution that I could use?

Best Answer

By default, the libvirt DHCP "server" is the gateway for the libvirt guests. If you want to specify a different setup, then you cannot use libvirt's built-in NAT. You need to create a custom virtual network, probably using brctl, and run a DHCP service on that interface that hands out whatever custom DHCP lease you want.

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