apt-get install bridge-utils

/etc/network/interfaces

iface br0 inet static
        address 192.123.12.2/24
        gateway 192.123.12.1
        dns-nameservers 192.123.12.1
        dns-search domain.de
        bridge_ports eth0
        bridge_waitport 0
        bridge_maxwait 0
        bridge_df 0
        bridge_stp off

auto net1
iface net1 inet manual
        pre-up ip tuntap add net1 mode tap
        pre-up ip link set net1 up
        pre-up ip link set net1 master br0

auto net2
iface net2 inet manual
        pre-up ip tuntap add net2 mode tap
        pre-up ip link set net2 up
        pre-up ip link set net2 master br0

auto net3
iface net3 inet manual
        pre-up ip tuntap add net3 mode tap
        pre-up ip link set net3 up
        pre-up ip link set net3 master br0

auto net4
iface net4 inet manual
        pre-up ip tuntap add net4 mode tap
        pre-up ip link set net4 up
        pre-up ip link set net4 master br0

auto net8
iface net8 inet manual
        pre-up ip tuntap add net8 mode tap
        pre-up ip link set net8 up
        pre-up ip link set net8 master br0

auto net9
iface net9 inet manual
        pre-up ip tuntap add net9 mode tap
        pre-up ip link set net9 up
        pre-up ip link set net9 master br0

Bridged-Netzwerk manuell einrichten

ip addr flush dev eth0
ip link add name br0 type bridge
ip link set eth0 master br0
ip addr add 192.123.12.2/24 dev br0
ip link set br0 up

ip tuntap add dev tap0 mode tap user $(whoami)
ip link set tap0 master br0
ip link set dev br0 up
ip link set dev tap0 up

ip link set eth0 nomaster
ip link delete br0 type bridge

route add default gw 192.123.12.1

Kernel Parameter

echo 0 > /proc/sys/net/bridge/bridge-nf-call-arptables
echo 0 > /proc/sys/net/bridge/bridge-nf-call-ip6tables
echo 0 > /proc/sys/net/bridge/bridge-nf-call-iptables

Für QEMU VM

qemu-system-x86_64 -m 4096 -cpu host -machine type=pc,accel=kvm -hda /media/ramdisk/vm0.img -vga std -k de -net nic,macaddr=52:54:00:12:34:00 -net tap,ifname=net0,script=no,downscript=no -boot c