This chapter has brought you up to date to fully understand the subsequent chapters. The following has been gone through thoroughly:
TCP/IP structure
IP protocol functionality and headers.
TCP protocol functionality and headers.
UDP protocol functionality and headers.
ICMP protocol functionality and headers.
TCP/IP destination driven routing.
All of this will come in very handy later on when you start to work with the actual firewall rulesets. All of this information are pieces that fit together, and will lead to a better firewall design.