Comment 14 for bug 1758037

If you have a system with libvirt and virt-manager installed, you can just create a virtual machine, then edit its configuration with "virsh edit" to att the following "<filterref>" section to its <interface>, then attempt to start the virtual machine:

    <interface type='network'>
      <source network='default'/>
      <filterref filter='clean-traffic'>
        <parameter name='CTRL_IP_LEARNING' value='dhcp'/>
        <parameter name='DHCPSERVER' value='192.168.122.1'/>
      </filterref>
    </interface>

If you've installed the debuginfo for libvirt, you can set a breakpoint on the function virNWFilterSNoopDHCPOpen() (which is the source of the bit of code I posted above).

I can provide more detailed step-by-step instructions if you need it, but didn't want to pollute the BZ with a long treatise on installing virt stuff if you already had it on.

If you need any assistance while doing this, you can find me (and several other libvirt developers) on IRC in the #virt channel on irc.oftc.net.