A method of interpreting a rule and a rule-interpreting apparatus for rule-based security apparatus, and an apparatus implementing the method. The method comprises the following steps: designating a suspicious timeslot; if any packet does not present in the designated timeslot, capturing current incoming packets or capturing other incoming packets in the designated timeslot next time; automatically associating the packets in the designated timeslot to form at least one traffic flow corresponding to a connection or call; analyzing the at least one traffic flow to select at least one suspicious target traffic flow; and outputting the at least one selected suspicious target flow.