Stops a packet capture.

        :param port_number: allocated port number

def stop_capture(self, port_number):
        """
        Stops a packet capture.

        :param port_number: allocated port number
        """

        if port_number not in self._mappings:
            raise DynamipsError("Port {} is not allocated".format(port_number))

        nio = self._mappings[port_number]
        yield from nio.unbind_filter("both")
        log.info('Ethernet hub "{name}" [{id}]: stopping packet capture on port {port}'.format(name=self._name,
                                                                                               id=self._id,
                                                                                               port=port_number))