Table Of ContentMastering Python Networking
Fourth Edition
Utilize Python packages and frameworks for network automation,
monitoring, cloud, and management
Eric Chou
BIRMINGHAM—MUMBAI
“Python” and the Python Logo are trademarks of the Python Software Foundation.
Mastering Python Networking
Fourth Edition
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First published: April 2016
Second edition: August 2018
Third edition: January 2020
Fourth edition: January 2023
Production reference: 1130123
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To my wife, Joanna, who inspired me to explore.
To my children, Mikaelyn and Esmie, may you find the fire to explore the world as well.
Foreword
The book you are holding in your hands or are reading on your screen has a power that can be
yours if you take time to study it. Programming can amplify your existing knowledge and skillset.
Many people are told they should learn programming and Python for their own sake. Program-
ming skills are in demand, so you should be a programmer. That is probably good advice. But
better advice would be to answer the question, “How can you take your existing expertise and
leap ahead of peers by automating and extending that experience with software skills?” This
book aims to do just that for network professionals. You’ll learn about Python in the context of
network configuration, administration, monitoring and more.
If you are tired of logging in and typing in a bunch of commands to configure your network,
Python is for you. If you need to be certain the network configuration is solid and repeatable,
Python is for you. If you need to monitor, in real-time, what is happening on the network, well,
you guessed it, Python is for you.
You are probably in agreement about learning software skills that can be applied to network
engineering. After all, terms like Software-Defined Networking (SDN) have been all the buzz
in the last few years. But why Python? Maybe you should learn JavaScript or Go or some other
language. Maybe you should just double down on Bash and shell scripting.
Python is well suited for network engineering for two reasons.
Firstly, as Eric will demonstrate throughout this book, there are many Python libraries (sometimes
called packages) designed specifically on network engineering. With libraries such as Ansible, you
can create complex network and server configurations using simple configuration files. Using Pex-
pect or Paramiko, you’ll be able to program against remote legacy systems as if they had their own
scripting API. If the gear you’re configuring has an API, chances are you can use a purpose-built
Python library to work with it. So clearly, Python is well-suited for the job.
Secondly, Python is special amongst programming languages. Python is what I call a full spectrum
language. My definition of this term is that it is both a language that is incredibly easy to get
started (print ("hello world" ) anyone?) and also very powerful, being the technology behind
incredible software such as YouTube.
This is not normal. We have solid beginner languages for quickly building software. Visual Basic
comes to mind here. So does Matlab and other commercial languages. Yet, when these are pushed
too far, they fall down badly. Can you imagine Linux, Firefox, or an intensive video game created
with any of these? No way.
At the other end of the spectrum, we also have very powerful languages such as C++, .NET, Java
and many others. C++ is, in fact, the language used to build some Linux kernel modules and large
open-source software such as Firefox to some degree. Yet, they are not beginner-friendly. You
have to learn about pointers, compilers, linkers, headers, classes, accessibility (public/private),
and on and on just to get started.
Python lives in both realms making it incredibly easy to be productive with just a few lines of
code and simple programming concepts. Yet it grows to be the language of choice for some of
the world’s most significant software behind YouTube, Instagram, Reddit, and others. Microsoft
chose Python as their language to implement the CLI for Azure (although you don’t have to know
or use Python to use their CLI of course).
So, here’s the deal. Programming is a superpower. It can take your network engineering expertise
and launch it into the stratosphere. Python is one of the world’s fastest growing and most pop-
ular programming languages. And Python has many highly polished libraries for working with
networks in many facets. Therefore, this book, Mastering Python Networking, combines all of these
and will change the way you think about networking. Enjoy the journey.
Michael Kennedy
Portland, OR
Founder of Talk Python
Contributors
About the author
Eric Chou is a seasoned technologist with over 20 years of experience. He has worked on some
of the largest networks in the industry while working at Amazon, Microsoft, and other Fortune
500 companies. Eric is passionate about network engineering, Python, and helping companies
build better automation culture.
Eric is the author of other top-selling books on security, data processing, and programming.
Eric holds multiple U.S. patents in IP telephony and networking. He shares his deep interest in
technology through his books, online classes, speaking engagements, and contributing to open
source projects.
I would like to thank the open source community members for generously sharing their compassion, knowledge,
and code. Without them, many of the projects referenced in this book would not have been possible. I hope I
made small contributions to the wonderful communities in my own way as well.
I would like to thank the Packt team for the opportunity to collaborate on the fourth edition of this book. Special
thanks to the technical reviewer, Josh VanDeraa, for generously agreeing to review this book.
To my family, your constant support and encouragement make me want to be the best version of myself. I love you.
About the reviewer
Josh VanDeraa is a 20-year networking veteran who has been doing network automation for
the past 7 years. He has worked in large enterprise retail, travel, managed services, and most re-
cently, professional services industries. He has worked on networks of all sizes, bringing multiple
different network automation solutions to the table to drive real value with Python, Ansible, and
Python web framework solutions.
Josh is the author of Open Source Network Management and maintains a blog site (https://josh-v.
com) to provide additional content to those on the web.
I’d like to thank my family first and foremost, who have allowed me the time to dive in and review the topic.
I would also like to thank Eric for taking the time to share his experiences. This is a tough thing to do and Eric
has done a masterful job at putting time and real-life experiences into the book to be consumed. I love how the
book has evolved over the revisions, with my first reading of the book coming in the second edition.
And lastly, I would like to thank the greater network automation community. This is a journey for all of the
individuals, no matter the organization. Please join, teach, and share your experiences with the community
so network automation can continue to evolve!
Join our book community
To join our community for this book – where you can share feedback, ask questions to the author,
and learn about new releases – follow the QR code below:
https://packt.link/networkautomationcommunity
Table of Contents
Preface xxi
Chapter 1: Review of TCP/IP Protocol Suite and Python 1
An overview of the Internet ������������������������������������������������������������������������������������������������� 3
Servers, hosts, and network components • 4
The rise of data centers • 5
Enterprise data centers • 5
Cloud data centers • 6
Edge data centers • 7
The OSI model �������������������������������������������������������������������������������������������������������������������� 8
The client-server model ���������������������������������������������������������������������������������������������������� 10
Network protocol suites ����������������������������������������������������������������������������������������������������� 11
The transmission control protocol • 12
Functions and characteristics of TCP • 12
TCP messages and data transfer • 12
The user datagram protocol • 13
The Internet protocol • 14
IP network address translation (NAT) and network security • 15
IP routing concepts • 15
Python language overview ������������������������������������������������������������������������������������������������ 16
Python versions • 17
Operating system • 17
