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Linux for Networking Professionals

You're reading from   Linux for Networking Professionals Securely configure and operate Linux network services for the enterprise

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Product type Paperback
Published in Nov 2021
Publisher Packt
ISBN-13 9781800202399
Length 528 pages
Edition 1st Edition
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Author (1):
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Rob VandenBrink Rob VandenBrink
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Rob VandenBrink
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Toc

Table of Contents (20) Chapters Close

Preface 1. Section 1: Linux Basics
2. Chapter 1: Welcome to the Linux Family FREE CHAPTER 3. Chapter 2: Basic Linux Network Configuration and Operations – Working with Local Interfaces 4. Section 2: Linux as a Network Node and Troubleshooting Platform
5. Chapter 3: Using Linux and Linux Tools for Network Diagnostics 6. Chapter 4: The Linux Firewall 7. Chapter 5: Linux Security Standards with Real-Life Examples 8. Section 3: Linux Network Services
9. Chapter 6: DNS Services on Linux 10. Chapter 7: DHCP Services on Linux 11. Chapter 8: Certificate Services on Linux 12. Chapter 9: RADIUS Services for Linux 13. Chapter 10: Load Balancer Services for Linux 14. Chapter 11: Packet Capture and Analysis in Linux 15. Chapter 12: Network Monitoring Using Linux 16. Chapter 13: Intrusion Prevention Systems on Linux 17. Chapter 14: Honeypot Services on Linux 18. Assessments 19. Other Books You May Enjoy

Troubleshooting an application – capturing a VoIP telephone call

To do this, I'll keep our same capture setup and make a call from the client phone on port G1/0/1 to the helpdesk call on G1/0/2. Capturing all the packets in and out of G1/0/1 should get us what we need – for this interval, the traffic in and out of G1/0/2 should be identical to G1/0/1 (just in the reverse direction).

To capture our text, we'll simply do a full capture; no filters are needed in this case. We started our capture, ensuring that we caught the start and end of the call (so we started the capture before the dial, and ended it after the hang-up).

With the capture completed, we can look at our PCAP in Wireshark – the example file for this lab is HelpDesk Telephone Call.pcapng, which is located in our GitHub repository at https://github.com/PacktPublishing/Linux-for-Networking-Professionals/tree/main/C11.

Let's look at packet 6, labeled Ringing. Exploring the application...

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