Years ago on the wall of an IT department, I spotted an innocent looking red box, labeled “Break In Case of Emergency”. Inside was a hefty wire-cutter – the ultimate firewall. The humor of this won’t be lost on security-minded folks. The job of a firewall is to block all traffic by default, allowing only certain traffic by exception. Considering only security and ignoring business requirements, the best firewall is one that allows no traffic to pass through.

