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

Examining the 11-field TCP header

TCP has an 11-field header. The fields hold the values that keep track of the conversation, as shown in the following diagram:

Figure 9.10 – The TCP header

TCP uses the field values to monitor the communication. Once all bytes have been received, TCP will indicate that the end device has successfully received all of the data. If there is trouble during the data transport, TCP will alert the other host of any missing segments.

In this section, we'll take a look at each of the header fields so that you have a better understanding of how TCP is able to provide reliable communication between hosts. I'll list the field and the size in the following manner, [Field: Size], when appropriate, so that you understand the values that comprise a TCP header.

Starting at the top of the TCP header in Frame 4 of HTTP.cap, we can see the label Transmission Control Protocol, as shown in Figure 9.8. Below the label, you...