1. A computer readable storage medium including a set of instructions executable by a processor, that cause the processor to perform a method for screening incoming data of a network, comprising: determining relationships between a plurality of existing rules in a rule set of a firewall used to screen the incoming data of the network, wherein the relationships include cause interactions and effect interactions among the existing rules; creating a representation of the relationships including the cause interactions and effect interactions; receiving a new rule to be inserted into the rule set; inserting further relationships between the new rule and the existing rules into the representation to create a modified representation; and determining, based on the modified representation, if a conflict is created by insertion of the new rule in the rule set.