The Israeli department of defence has one of the strictest information security guidelines in the world, and a part of these guidelines is the requirement to have complete physical separation between the public and internal networks. A regular firewall just won't do, and this requirement gave birth to the concept of the
Air-Gap, a revolutionary product for its time. The Air-Gap and e-Gap products
used a physical switch that enabled the transfer of data from one network to the other, but still kept them physically disconnected. One might think of this like a shuttle transferring passengers from one land-mass to another. Whether this is more secure than advanced software-based firewalls can be debated, but the product did meet the guidelines and became very successful in Israel.
Building on this success, Whale Communications distributed the e-Gap appliance throughout the world, and continued its development. In 2006, Whale Communications was purchased by Microsoft, and the next version, named Intelligent Application Gateway or IAG, had similar capabilities, but ditched the physical switch and the dual-server design with a software firewall—Microsoft's ISA 2006 server.