Chapter 3. TCPIP for Firewalls

Chapter 3. TCP/IP for Firewalls

Much like humans may speak English, German, or Russian, computers may "speak" any number of languages: IPX/SPX, AppleTalk, and TCP/IP being just a few of them. Because of the portability and scalability of TCP/IP, TCP/IP has been settled on as the de facto standard method for providing communication services between hosts on a network and in particular across the Internet. Much like a human language, TCP/IP has a defined structure and set of rules that control how hosts communicate. Therefore, those who learn the structure and rules of TCP/IP, learn and become proficient in the language so to speak, will be able to truly understand how systems are communicating with each other.

This proficiency in TCP/IP is a critical skill for the firewall administrator because firewalls exist largely to protect systems from being accessed using TCP/IP. By understanding the intricacies of TCP/IP, a firewall administrator is much better equipped to effectively protect and defend systems from malicious access that uses TCP/IP as the communications protocol. Indeed, many security exploits and vulnerabilities that exist are based on taking advantage of misconfigurations and poor implementation of the TCP/IP protocols, applications, and services themselves.