IntroductionHistory of FirewallsWhy Firewalls BeganTypes of FirewallsFirewall InnovationsPacket FiltersHow Packet Filters WorkAdvantagesDisadvantagesApplication Layer GatewaysHow Application Gateways WorkAdvantagesDisadvantagesStateful InspectionHow Stateful Inspection WorksAdvantagesPerimeter, Internal, and Web SecurityPerimeterInternalWebINSPECT ScriptFireWall-1 Decision MakingDaemon Thought ProcessSummarySolutions Fast TrackHistory of FirewallsFirewall InnovationsPacket FiltersApplication Later GatewaysStateful InspectionPerimeter, Internal, and Web SecurityINSPECT ScriptFireWall-1 Decision MakingFrequently Asked Questions