In this chapter, we took a close look at the Purdue model and how it allows vendors to adapt their ICS (security) offering to the enterprise model with more ease. Then, we looked in detail at the CPwE architecture, which is a prime example of the adaptation of the Purdue model by ICS and network technology vendors Rockwell Automation and Cisco.
The chapter concluded with a brief introduction to the defense-in-depth model and explained how that model can be applied to create a holistic security program. The next chapter will be a detailed explanation of the defense-in-depth model.