1. An apparatus comprising: matching logic configured to concurrently evaluate packet header information against respective entries of a rule set coded in storage; and a hash generator for calculating a hash result relative to the evaluated packet information, the hash generator including intermediate and final portions and a filtration stage coupled therebetween, wherein the intermediate portion is configured as a chain of hash-intermediate stages each coupled to calculate a rule entry evaluation-specific contribution for possible inclusion in the hash and, for lower-order ones of the hash-intermediate stages, for possible propagation down chain and inclusion in a next higher-order hash-intermediate stage contribution, and wherein the filtration stage is selective for a rule entry-specific contribution from a particular one of the hash-intermediate stages for supply to the final portion for use in completing calculation of the hash result.