In this chapter, we covered some of the concepts in telecommunications and the network security domain.
We've revised Open System Interconnect (OSI) and the TCP/IP protocol suite. OSI forms the baseline for other models such as TCP/IP. There are seven layers in an OSI model, with the layers stacked. Each layer has a communication mechanism using protocols. A protocol or an implementation of it may have vulnerabilities that can be exploited by threat agents. Countermeasures have to applied to improve the security.
In the next chapter, we will cover the next four layers in the OSI model, the application of cryptography in communication security, and concepts related to securing network components.