def create_ipv6_nat_rule(chain, bridge, proto, host_port, container_ip, container_port):
    """return a iptables v6 nat rule for forwarding a host port to a container IP:port"""
    return '-A {chain} ! -i {bridge} -p {proto} -m {proto}' \
           ' --dport {host_port} -j DNAT' \
           ' --to-destination [{container_ip}]:{container_port}'.format(chain=chain,
                                                                        bridge=bridge,
                                                                        proto=proto,
                                                                        host_port=host_port,
                                                                        container_ip=container_ip,
                                                                        container_port=container_port)