In industrial and enterprise networks, firewalls are commonly used for protection. However, it is recommended to also have at least one layer of unidirectional gateway technology in the defense architecture, particularly at the IT/OT interface. This may be confusing to security practitioners who mistake unidirectional gateways for unidirectional firewalls.

This eBook explains the difference between firewalls and unidirectional gateways, provides an overview of firewall principles, and compares the effectiveness of these two network perimeter protection technologies. Waterfall Security’s conclusion is that unidirectional gateways are stronger than firewalls, are easy to implement, and significantly reduce costs at the boundary between control-critical and business-critical networks.