Manually running KVM on Ubuntu 12.10 (without virt-manager c.s.)

Did you have a running bridged networking KVM setup on your previous Ubuntu installation, but are things no longer working for you under Ubuntu 12.10 (Quantal)? Do you get:

/etc/kvm/kvm-ifup: could not launch network script
kvm: -net tap,vlan=0: Device ‘tap’ could not be initialized

Although it might be easier to start using virt-manager and friends to manage your virtual machines, a quick way to get things running again is simply create /etc/kvm/kvm-ifup with the following contents:


switch=$(ip route ls | awk ‘/^default / { for(i=0;i

Don’t forget to make it executable:

chmod a+rx /etc/kvm/kvm-ifup

And you’re ready to go! For more information about manually running KVM, please see the following documentation page on