1. A process of filtering packet data in a network device, said process comprising: applying at least one mask to a portion of an incoming packet; extracting a field from the portion of the incoming packet; searching a rules table for a matching value for the extracted field; recording a search result as one of a hit and a miss depending on the matching value; accessing a combination table based on the at least one mask; combining said one of the hit and the miss with another search result to obtain a combined search result; and executing one of a hit action and a miss action from the combination table based on the combined search result.