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

Stepping through the DORA process

The DHCP process is an efficient way to provide addresses to clients. Because we want our IP address quickly, it uses User Datagram Protocol (UDP) as the transport layer protocol.

DHCP uses the following UDP ports:

  • Clients use port 68.
  • Servers and relay agents use port 67.

DHCPv6 uses the following UDP ports:

  • Clients use port 546.
  • Servers and relay agents use port 547.

You will see these ports in use when we examine DHCP traffic.

The DHCP process progresses through various states during a transaction, as outlined in the next section.

Moving through DHCP states

During the process of a DHCP transaction, the client can be in one of six states. Understanding these states and what transpires will help during troubleshooting. These DHCP states are as follows:

  • Initiate: The client begins the process by sending a broadcast on the network in search of a DHCP server.
  • Select: The client will select...