[libvirt-users] error configuring a public bridge --> uvt-kvm: error: libvirt domain 'newtest' has no NIC MACs available.

Hi all, First at all, excuse if this is not the right place for sending this email. I'm using ubuntu 14.04 server edition and i'm trying to deploy some virtual machines in a server in such a way that they are visible in the same network that the host machine. The tools I'm using are the uvtool package and libvirt. The error I'm getting is the following: "uvt-kvm: error: libvirt domain 'newtest' has no NIC MACs available." Here I'm providing the quickest way (I think) of reproducing my problem. The steps to follow would be: 1) Creating a bridge. This is my /etc/network/interfaces # This file describes the network interfaces available on your system # and how to activate them. For more information, see interfaces(5). # The loopback network interface auto lo iface lo inet loopback auto em1 iface em1 inet manual auto br0 iface br0 inet static address 9.109.124.62 network 9.109.124.0 netmask 255.255.255.0 broadcast 9.109.124.255 gateway 9.109.124.1 #iface br0 inet dhcp bridge_ports em1 bridge_stp off bridge_fd 0 bridge_maxwait 0 dns-search xx.xx.xx.xx dns-nameservers 192.168.122.1 9.0.146.50 9.0.148.50 2) downloading a trusty tahr cloud image and run it uvt-simplestreams-libvirt sync release=precise arch=amd64 uvt-kvm create test release=trusty 3) duplicate the xml generated when running the machine in order to modify the network interface by the bridge one. In the XML I also remove the uuid and change the VM name. sudo mv /etc/libvirt/qemu/test.xml /etc/libvirt/qemu/test2.xml In test 2 the most relevant change is replacing <interface type='network'> <mac address='52:54:00:86:7a:31'/> <source network='default'/> <model type='virtio'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> </interface> by <interface type='bridge'> <source bridge='br0'/> <model type='virtio'/> </interface> 4) Once I have my new XML, I define and start the new machine uvt-kvm destroy test virsh undefine test sudo virsh define /etc/libvirt/qemu/test2.xml virsh start newtest (newtest is the name provided in test2.xml) 5) Up to this point everything seems to be fine, but if i run a wait command i get the error uvt-kvm wait newtest --insecure uvt-kvm: error: libvirt domain 'newtest' has no NIC MACs available. I have checked the xml generated when defining newtest and there is a MAC in there, so it is not a problem generating a MAC address. Also the interface br0 is visible for virsh: virsh iface-list Name State MAC Address --------------------------------------------------- br0 active xx:xx:xx:xx:xx:xx lo active 00:00:00:00:00:00 I have been googling for a while and couldn't find anything but this: http://pastebin.com/em0hmy4t That tries something similar and falls in the same error. Any help will be very much appreciated. It is the first time i send anything to one of this mail lists, so, please, if you need me to provide any other info, tell me. Thanks! Jordi