Isso funciona: link
comandos principais:
ifconfig bat0 up promisc
...
ifconfig eth0 up promisc
brctl addbr br-freifunk
brctl addif br-freifunk bat0
brctl addif br-freifunk eth0
...
dhclient br-freifunk
e para pará-lo:
brctl delif br-freifunk bat0
brctl delif br-freifunk eth0
brctl delbr br-freifunk
ifconfig br-freifunk down
ifconfig bat0 down -promisc
ifconfig eth0 down -promisc
batctl if del $IFACE