Book Image

Learn Wireshark, - Second Edition

By : Lisa Bock
5 (1)
Book Image

Learn Wireshark, - Second Edition

5 (1)
By: Lisa Bock

Overview of this book

Wireshark is a popular and powerful packet analysis tool that helps network administrators investigate latency issues and potential attacks. Over the years, there have been many enhancements to Wireshark’s functionality. This book will guide you through essential features so you can capture, display, and filter data with ease. In addition to this, you’ll gain valuable tips on lesser-known configuration options, which will allow you to complete your analysis in an environment customized to suit your needs. This updated second edition of Learn Wireshark starts by outlining the benefits of traffic analysis. You’ll discover the process of installing Wireshark and become more familiar with the interface. Next, you’ll focus on the Internet Suite and then explore deep packet analysis of common protocols such as DNS, DHCP, HTTP, and ARP. The book also guides you through working with the expert system to detect network latency issues, create I/O and stream graphs, subset traffic, and save and export captures. Finally, you’ll understand how to share captures using CloudShark, a browser-based solution for analyzing packet captures. By the end of this Wireshark book, you’ll have the skills and hands-on experience you need to conduct deep packet analysis of common protocols and network troubleshooting as well as identify security issues.
Table of Contents (28 chapters)
1
Part 1 Traffic Capture Overview
6
Part 2 Getting Started with Wireshark
11
Part 3 The Internet Suite TCP/IP
16
Part 4 Deep Packet Analysis of Common Protocols
21
Part 5 Working with Packet Captures

Sending ICMP messages

ICMP messages are grouped into two categories: error reporting and queries. Some messages are specific to each version; however, a few are common to both versions, as shown here:

Figure 12.10 – ICMP messages

For both categories, each ICMP packet has typecode, and checksum fields. The payload for queries is different from error messages, as each has a different purpose, as we'll see in the following sections. 

Let's start with a review of how ICMP reports errors.

Reporting errors on the network

ICMP error messages report on network issues that prevent data from being delivered. Commonly sent error messages are grouped into categories that have a specific purpose, and include the following:

  • Destination unreachable is where a router informs the host that the requested destination address can't be reached.
  • Time exceeded is sent when either...