UDP6_DEV_NAME
udp6fd = open(UDP6_DEV_NAME, O_RDWR | O_NONBLOCK, 0);
error("Couldn't open UDPv6 device (%s): %m", UDP6_DEV_NAME);
udp_dev_name = UDP6_DEV_NAME;
udp_dev_name = UDP6_DEV_NAME;
udp_dev_name = (af == AF_INET6 ? UDP6_DEV_NAME : UDP_DEV_NAME);
udp_dev_name = UDP6_DEV_NAME;