An important concept in establishing a connection-oriented session is to outline the parameters of the conversation before any data is exchanged. In this chapter, we studied how TCP begins a conversation by using a three-way handshake and took a closer look at each step of the handshake. We saw how, once the handshake is complete, the operating system creates a socket so that data exchange can take place.

In addition, we reviewed the TCP options that are exchanged during the three-way handshake, such as SACK, MSS, and timestamps. This chapter also explained the TCP protocol preferences and outlined how you can modify protocol preferences in Wireshark. Then, we saw how TCP ends a session by exchanging FIN packets that signal each host to close the session.

IP is the other dominant protocol in the TCP/IP suite. In the next chapter, we will take a closer look at IPv4 and IPv6. So that you have a better understanding of this network layer protocol, we'll begin with a thorough overview of IPv4 and examine the header format along with each of the field values. We will then take a look at IPv6 along with the corresponding header format and the field values. Because IPv4 is a completely different format to IPv6, we will address how the two can coexist by using various tunneling protocols when in a dual-stack environment.