Unidirectional gateways are a plug-n-play solution replacing one layer of firewalls in an industrial network environment, typically between IT and OT environments. Unlike firewalls, Waterfall’s Unidirectional Gateway products are a combination of hardware and software. The hardware is physically able to send information in only one direction: usually from a high-criticality network to a lower-criticality network. The unidirectionality of Waterfall’s Unidirectional Gateways is physically enforced, in the gateway hardware. Customers can be confident of the unidirectionality of Waterfall’s gateways because the products are Common Criteria certified to be unidirectional with a high degree of confidence, even in the face of the most sophisticated nation-state and organized crime attacks possible.