Updated QEMU-Admin tool with host <->guest network bridging

Last friday afternoon, I quietly pushed out an update to the QEMU admin tool (being used for the OLPC SDK) which allows QEMU virtual machines to be connected up to the host network stack. Previously only a private VM-to-VM networks over IP multicast, or SLIRP-based outbound TCP only networks were working with QEMU-Admin. This new capability sets up a private network using VDE (Virtual Distributed Ethernet) switch to which QEMU VMs can connect. The dnsmasq daemon provides DNS & DHCP to this private network, allowing for zero-config networking in the QEMU guests. Finally a little VDE+IPTables magic connects the virtual network to the real host network via a TAP device. For those using NetworkManager, there is even an action script for the NetworkManager dispatcher, to automatically update the IPTables forwarding/masquerading rules when you switch between wired & wireless modes.
There’s probably still a number of bugs in this setup, but this host network bridging is the next step towards a fully automated harness for testing the OLPC ‘firmware’ images. For further info on setting up the network bridge, I’ve written a short set of instructions