Chapter 28

Chapter 29

Chapter 30

The previous two parts thoroughly explored versions 4 and 6 of the Internet Protocol (IP). IP is a very capable protocol that provides the functionality necessary to address, package, and deliver information on TCP/IP internetworks. However, IP was intentionally designed to be simple, without a lot of bells and whistles. To deal with special needs, a number of other protocols have been created to enhance or expand on IP's capabilities. I call these IP-related feature protocols.

This part contains three chapters that provide complete explanations of three of the more important IP-related feature protocols. The first chapter describes IP Network Address Translation (IP NAT or NAT), which allows private networks to be accessed on the Internet and IP addresses to be shared. The second chapter explores IP Security (IPsec), a set of subprotocols that allows IP datagrams to be authenticated and/or encrypted. The third chapter covers the Mobile IP protocol, which corrects some of the problems associated with using TCP/IP with mobile hosts.