return nil, errNoAvailableAddress
	}
	ip, ok := hasRoutableIP(network, ifi)
	if !ok {
		return nil, errNoAvailableAddress
	}
	return ip, nil
}

// LoopbackInterface returns an available logical network interface
// for loopback test.
func LoopbackInterface() (*net.Interface, error) {
	ift, err := net.Interfaces()
	if err != nil {
		return nil, errNoAvailableInterface
	}
	for _, ifi := range ift {