In one example, a method includes for each one time period of a plurality of time periods performing a weighted random selection of a first set of intrusion detection/protection system rules from a plurality of rules, each rule of the plurality of rules having an associated probability of selection, preparing a packet inspection plan including the first set of intrusion detection/protection system rules, and sending the packet inspection plan to a network distribution device to inspect packets according to the packet inspection plan. Related apparatus and methods are also described.