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

Creating I/O graphs

An I/O graph provides a way to analyze traffic flowing in both directions and can be created using a live capture or an existing trace file.

To generate graphs on a specific stream, return to bigFlows.pcap. In the display filter, enter tcp.stream eq 198 and run the filter. Once Wireshark presents the information, we'll reduce the file by going to File | Export Specified Packets…, which will bring up this window:

Figure 19.7 – Export Specified Packets window

Make sure you have selected All Packets | Displayed, as shown in Figure 19.7. Then, save the file as Flow198.pcap.

Close bigFlows.pcap and then open Flow198.pcap, where we will see evidence of a congested network.

Examining errors

Within Flow198.pcap, you'll see several areas of concern, as the intelligent scroll bar is littered with black lines, which generally indicates signs of latency. By clicking on one of the black striped areas on the scroll...