Chapter 12: Discovering ICMP

Everyone is familiar with the Internet Protocol (IP), which is responsible for routing and addressing traffic. However, many are not as familiar with the Internet Control Message Protocol (ICMP), a powerful protocol that plays a major role in delivering data. In this chapter, we'll learn about ICMP, the companion protocol to IP, which works in the network layer of the OSI model. We'll begin with an overview so that you have a general understanding of the main functions of ICMP.

We will then evaluate both ICMP (used with IPv4) and ICMPv6 (used with IPv6) so that you can compare some of the main differences. In addition, you'll get a better understanding of the two types of messages: error reporting and queries. We'll then look at common type and code values, along with a discussion on which types of ICMP messages are no longer used. We'll finish with a discussion on how malicious...