[libvirt-users] Can't NAT in KVM

[Borden Rhodes]

Good morning, list,

I've been trying to get my KVM virtual machines to connect to the
Interwebs for the last 3 hours with no success. I'm running Debian
Wheezy (fully patched) and building virtual machines using KVM in Virt
Manager.

With the default, factory settings shown in virt manager, I have a
default virtual network with the device name virbr0, which starts on
boot and uses the default IPv4 subnets. I also have the default lo
(loopback) network interface.

I have tried creating a Windows 8 Release Preview machine and a
Kubuntu Live CD machine. Despite recognising the hardware and network
interface, neither machine will connect to the Internet. From what I
can see in both virtual machines, it seems that neither is getting a
DHCP lease from virbr0. I'm not sure what's broken or where to start
looking for trouble because both the logs and the documentation are
fairly sparse.

Other possibly relevant information: I have a simple firewall
configured with Firestarter in Wheezy. I use Network Manager to manage
my only wireless connection to the world. I don't want to set up any
fancy bridging or override /etc/interfaces because I only use virtual
machines rarely but I rely on Network Manager to set up my laptop's
networks so I don't have to.

Any suggestions on how I can plug the v-machines to the web?

With thanks,

Borden