Endpoint security needs to span across hardware, firmware, and software, including network and application interfaces. To implement a trusted and resilient ecosystem of IIoT endpoints and subsystems, a variety of technologies come into play, as shown in the following diagram, which stacks the security technologies into hardware, intermediate, enhanced, and intelligent security layers. The main purpose of this classification is to give the reader an idea of the relative role and importance of each of these technologies that are available to protect endpoints:

Subsequent sections of this chapter will further elaborate on some of these techniques.