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

Evaluating queries and responses

DNS queries and responses are pretty straightforward. A client sends a query to a DNS server for an IP address and the server responds with the information. In this section, we'll take a look at some of the behavior during a transaction, such as caching responses, along with monitoring average response times during a transaction using Wireshark.

We'll then evaluate what happens when we need to troubleshoot DNS, and how nslookup helps to check and verify the response. Finally, we'll take a look at spoofing DNS, and how we can secure the process.

Let's start with learning how caching plays a part in the DNS process.

Caching a response

Anything on the network has a time limit. DNS is no exception. When a server returns a response, there are several elements within the answer. Within that response is the TTL value, which reflects how long the record can live in the cache before disappearing.

The TTL value can vary by system...