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

Discovering the four-field UDP header

UDP has a four-field header that holds the values that keep track of the conversation, as shown in the following diagram:

Figure 9.25 – The UDP header

Now, let's take a look at each of the four UDP headers.

Analyzing the UDP header fields

Starting at the top of the UDP header, we can see User Datagram Protocol, followed by a summary of what the header represents. Below the header and summary are the UDP header fields, as shown here:

Figure 9.26 – The UDP header as shown in Wireshark

Unlike TCP, UDP has a simple header, with no additional communication details listed, such as Timestamps or SEQ/ACK analysis.

After the header, you will see the following:

  • Source Port 16-bit: The source port field is the port on the sender's side. In Frame 1, the sender is a DNS client, using Source Port: 54585, which is not associated with any application; it is an ephemeral...