SERVER_PORT
err = make_sockaddr(AF_INET, VETH1_ADDR, SERVER_PORT, &saddr, &saddr_len);
srv_fd = start_server(family, SOCK_DGRAM, NULL, SERVER_PORT, 0);
sfd = start_server_str(AF_INET6, SOCK_DGRAM, "fb00::6", SERVER_PORT, NULL);
server_addr.sin6_port = htons(SERVER_PORT);