Basically implement this but for Debian:
http://people.redhat.com/berrange/olpc/sdk/network-bridge.html

The package would use vde_switch to create a tun/tap network interface
named "qemu". This interface is auto-configured at boot time:
- with a fixed IP address
- dnsmasq runs on it to provide DNS+DHCP for the qemu guests
- optionnaly it setups forwarding + ip masquerading so that the qemu
virtual network has access to the internet (or the real LAN)

Then any user in the vde2-net can start a virtual machine connected on the
network (and reachable from the host, contrary to the default user network
stack solution provided by qemu) with a command like this one:
$ vdeq qemu -m 128 -hda hda.bin -net nic,macaddr=$mac -net vde,sock=/var/run/vde2/qemu.ctl

Other pointers on the same topic:
http://alien.slackbook.org/dokuwiki/doku.php?id=slackware:vde

Currently I configured something like this manually in
/etc/network/interfaces:
auto qemu
iface qemu inet static
    address 10.0.2.1
    netmask 255.255.255.0
    vde2-switch -
    up /etc/init.d/dnsmasq restart || true
    up echo 1 > /proc/sys/net/ipv4/ip_forward
    up iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
    up iptables -t nat -A POSTROUTING -o eth1 -j MASQUERADE
    down iptables -t nat -F

and my dnsmasq.conf has the following changes:
listen-address=10.0.2.1
bind-interfaces
dhcp-range=10.0.2.15,10.0.2.100,12h

Add some debconf prettyness to ask for the default address/netmask, etc and
this package would be really useful for users which are used to make
experiences in several virtual machines. :-)

Cheers,

[Replying to an old bugreport...]
05.04.2007 18:13, Raphael Hertzog wrote:


This is about the same thing as libvirt does internally using some GUI
sugar.  I don't think we want to duplicate this functionality.  So
marking this as wontfix for now.

Thank you for your patience!

/mjt