A method for filtering data packets at a firewall system is disclosed that includes receiving a data packet having a plurality of fields at a processor. Determining with the processor whether a precondition exists for one or more of the plurality of fields, where an action is associated the precondition. Performing the action associated with the precondition on the data packet with the processor if it is determined that the precondition exists for one or more of the plurality of fields. Processing the data packet using a plurality of rules with the processor if it is determined that the precondition does not exist for the one or more of the plurality of fields. Processing a second data packet by making an incremental change to the plurality of rules.
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