@classmethod
def find_free_port(cls, base_port, socket_path):
    """start base_port to lookup a free port"""
    while base_port < 60000:
        if cls.is_open(ip='127.0.0.1', port=base_port):
            base_port += 1
        else:
            try:
                cls.__check_socket('{}/{}'.format(socket_path, base_port))
                return base_port
            except FileExistsError as e:
                base_port += 1
