Book Image

Mastering OpenVPN

By : Jan Just Keijser, Eric F Crist
Book Image

Mastering OpenVPN

By: Jan Just Keijser, Eric F Crist

Overview of this book

Security on the internet is increasingly vital to both businesses and individuals. Encrypting network traffic using Virtual Private Networks is one method to enhance security. The internet, corporate, and “free internet” networks grow more hostile every day. OpenVPN, the most widely used open source VPN package, allows you to create a secure network across these systems, keeping your private data secure. The main advantage of using OpenVPN is its portability, which allows it to be embedded into several systems. This book is an advanced guide that will help you build secure Virtual Private Networks using OpenVPN. You will begin your journey with an exploration of OpenVPN, while discussing its modes of operation, its clients, its secret keys, and their format types. You will explore PKI: its setting up and working, PAM authentication, and MTU troubleshooting. Next, client-server mode is discussed, the most commonly used deployment model, and you will learn about the two modes of operation using "tun" and "tap" devices. The book then progresses to more advanced concepts, such as deployment scenarios in tun devices which will include integration with back-end authentication, and securing your OpenVPN server using iptables, scripting, plugins, and using OpenVPN on mobile devices and networks. Finally, you will discover the strengths and weaknesses of the current OpenVPN implementation, understand the future directions of OpenVPN, and delve into the troubleshooting techniques for OpenVPN. By the end of the book, you will be able to build secure private networks across the internet and hostile networks with confidence.
Table of Contents (17 chapters)
Mastering OpenVPN
About the Authors
About the Reviewers


Scripting and plugins are powerful tools to extend OpenVPN. It allows an administrator to integrate OpenVPN better into an existing infrastructure, for example, by enabling authentication against a separate backend system or by recording usage statistics of a client.

Writing OpenVPN scripts can be tricky, as special care needs to be taken about the timing of the scripts. The current version of OpenVPN is monolithic and single-threaded, which means that a lengthy or misbehaving server-side script can block the entire VPN for all users.

It is also important to understand the flow and order in which the scripts are called. In this chapter, we explored how this order works and which environment variables are present to each of the server- and client-side scripts.

In the next chapter, we will see more graphical user interfaces, as we dive into the use of OpenVPN on smart phones, tablets, and other mobile devices.