Summary

As mentioned earlier in this chapter, we cannot hope to cover TCP/IP as well or as effectively as W. Richard Stevens and Gary Wright did in the TCP/IP Illustrated books. We used them before we wrote this book and have no doubt we will continue to use them after. So do yourself a favor and go pick up a copy; we cannot recommend them enough when it comes to a definitive guide on TCP/IP.

That being said, this chapter should serve as a very basic reference to the mechanisms by which the Internet Protocol will traverse a firewall at Layers 3 and 4. In later chapters we also cover firewalling at Layer 2 of the OSI modelto give a complete picture of the capabilities of netfilter and iptables.