ifc=$1
killpid /var/run/dnsmasq.$ifc.pid
killpid /var/run/dhclient.$ifc.pid
killpid /var/run/dhclient-v6.$ifc.pid
ip -4 addr flush dev $ifc label $ifc:0
ip -4 addr flush dev $ifc label $ifc
ip link set dev $ifc down