One embodiment creates a model of the traffic through a network firewall and uses that model to dynamically manipulate the network firewall. The firewall model defines nodes, connections between the nodes, and firewall rules applicable to the nodes, the connections between the nodes, or a combination thereof. Each of the nodes represents simultaneously a source and a destination for data packets. The firewall rules include dynamic chains of rules having defined places where firewall rules may be dynamically inserted into or deleted from the firewall while the firewall is operating on one or more machines connected to network segments where the nodes reside.