### Connect a qemu guest to real network.

* Guest: Debian GNU/Linux - eth0
* Host: Debian GNU/Linux - eth0.201

    guest      host        host           host
    eth0 <---> tap0 <---> bridge0 <---> eth0.201 <---> real network

* One time:
    apt-get install bridge-utils
    apt-get install uml-utilities
    apt-get install vlan

* Bridge connection with vlan
    As root:
        vconfig add eth0 201
        tunctl -t tap0 -u username
        brctl addbr bridge0
        brctl stp bridge0 off
        brctl addif bridge0 eth0.201
        brctl addif bridge0 tap0
        ifconfig eth0.201 up
        ifconfig tap0 up
        ifconfig bridge0 up
        
* Bridge connection to physical interface
    As root:
        tunctl -t tap0 -u username
        ifconfig eth0 0.0.0.0
        brctl addbr bridge0
        brctl stp bridge0 off
        brctl addif bridge0 eth0
        brctl addif bridge0 tap0
        ifconfig eth0 up
        ifconfig tap0 up
        ifconfig bridge0 192.168.45.X netmask 255.255.255.0 up
        route add default gw 192.168.45.Z

* NAT connection
    As root:
        tunctl -t tap0 -u username
        ifconfig tap0 192.168.45.1 netmask 255.255.255.0 up
        echo 1 > /proc/sys/net/ipv4/ip_forward
        iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

* As normal user, run the qemu guest:
    qemu-system-x86_64 \
        -name DEVICE1 \
        -m 512 \
        -smp cpus=1 \
        -enable-kvm \
        -hda device1.qcow2 \
        -serial telnet::2000,server,nowait \
        -monitor tcp:127.0.0.1:4000,server,nowait \
        -display none \
        -daemonize \
        -net none \
        -net nic,model=e1000,vlan=1,macaddr=00:01:00:ff:01:01 \
        -net nic,model=e1000,vlan=2,macaddr=00:01:00:ff:01:02 \
        -net nic,model=e1000,vlan=3,macaddr=00:01:00:ff:01:03 \
        -net nic,model=e1000,vlan=4,macaddr=00:01:00:ff:01:04 \
        -net tap,vlan=1,ifname=tap0,script=no,downscript=no \
        -net socket,vlan=2,udp=127.0.0.1:9012,localaddr=:9002 \
        -net socket,vlan=3,udp=127.0.0.1:9013,localaddr=:9003 \
        -net socket,vlan=4,udp=127.0.0.1:9014,localaddr=:9004