KVM / Virt-manager / Bridging

I wanted my VMs bridged onto my LAN so they would be publicly accessible, but virt-manager only had options for creating new, private bridges. However, it turns out that if you create the bridge yourself, libvirt will use it. So, in /etc/network/interfaces:

auto virbr0
iface virbr0 inet manual
pre-up ifconfig eth1 down
pre-up brctl addbr virbr0
pre-up brctl addif virbr0 eth1
pre-up ifconfig eth1 up
post-down ifconfig eth1 down
post-down brctl delif virbr0 eth1

Then when libvirt-bin tries to find / create the "default" network on virbr0, it uses the already created one, and the guests are then bridged with the rest of the network. Note that adding this config on eth1 stopped networkmanager from working for eth0, so I had to set up eth0 in interfaces too. Having this setup on a single port should be similar (I would guess that replacing "manual" with "dhcp" would work?)