1. A packet switching device configured for processing packets, the packet switching device comprising: a plurality of interfaces configured to receive and send packets; one or more physical processors and physical memory configured to implement a plurality of firewalls, with each of the plurality of firewalls configured to perform firewall functionality on packets, with each firewall of the plurality of firewalls associated with a plurality of accesses; and routing or switching or control functionality configured to control the processing and movement of packets between the plurality of interfaces and said one or more physical processors and physical memory; wherein each interface of the plurality of interfaces is mapped to both a mapped firewall of the plurality of firewalls and an access of said accesses of the mapped firewall; wherein said performance of said firewall functionality performed on a particular packet by a particular firewall of the plurality of firewalls is determined based on a particular entry access and a particular exit access of said accesses of the particular firewall determined based on the routing of the particular packet between the plurality of interfaces, and programming of said firewall functionality based on the particular entry access and on the particular exit access; and wherein the packet switching device is configured to successively apply, to the particular packet, a first particular virtual firewall of the plurality of firewalls and then a second particular virtual firewall of the plurality of firewalls.