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firewalls and fate zones: operational impact. Terry Gray University of Washington S@LS workshop, Chicago 12 August 2003. firewall types. conventional integrated logical end-point. perimeters. physical topology: enterprise multi-subnet subnet sub-subnet endpoint logical topology:
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firewalls and fate zones: operational impact Terry Gray University of Washington S@LS workshop, Chicago 12 August 2003
firewall types • conventional • integrated • logical • end-point
perimeters • physical topology: • enterprise • multi-subnet • subnet • sub-subnet • endpoint • logical topology: • VLANs w/firewalls between • logical firewalls • IPSEC trust relationships
issues • relation of NetOps and SecOps • central vs. decentralized control • stateful vs. not-stateful blocking • firewalling policy by • device MAC • device IP • user identity • policy definition, impacted users, enforcement point
perimeter protection paradoxes • value vs. effectiveness • small is beautiful, but costly • end-point is best, but hardest to do • border vs. subnet firewalls--departments: both share and span subnets! • border: biggest vulnerability zone • border: easier to debug intra-campus problems • border: simpler rules? • lowest common denominator policy • avoid cross-subnet holes for bad protocols • still need per-address holes
incident response • enet port disabling • TCP/UDP port blocking • IP blocking • NAT traceability • blocking hi-numbered ports without stateful firewalls