The internal interface is an interface that some FortiGate models have by default (some models refer to this as the LAN interface). This interface contains a number of physical ports that are all treated as a single interface by the FortiGate unit. This allows you to configure access for the entire Local Area Network at the same time, rather than configuring each port individually.
Technical Writer at Fortinet
Bruce has been working with computers, and related technology, since before the World Wide Web was a thing. He has worked in system and network administration. He has even dabbled in technical support. He has made the switch to technical writing as part of his deep, dark and dastardly plan to make the arcane machinations of IT technology more easily understood by the poor folks who use it. That, and the voices in his head told him it was good idea. Never argue with the voices in your head. People will start to stare.