A computer system enforces network security policy by pre-classifying network traffic. Unidimensional pre-classifier filters analyze network traffic to populate a pre-classifier bit array. Rather than having filter explosion with the creation of multidimensional filters, the pre-classifier bit array is used by other layers and/or filters to enforce network security policy. Further, reclassification of network traffic due to network security changes is streamlined due to the inclusion of pre-classifier layers and the pre-classifier bit array.