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

Chapter 2. Point-to-point Mode

At first, point-to-point mode using pre-shared keys was the only available option when using OpenVPN. Nowadays, there are multiple ways to use OpenVPN, but point-to-point mode still has its uses. The term point-to-point mode using pre-shared keys is often abbreviated to pre-shared keys.

In point-to-point mode, OpenVPN is configured using pre-shared secret keys for predefined endpoints, and only a single endpoint can connect to a server instance at a time. The term server can be considered misleading, as both endpoints are more or less equal when it comes to functionality. The endpoint that initiates the connection is considered the client, the other endpoint is considered as the server.

We will start off with a demonstration of a very basic example. After that, we will discuss more features that OpenVPN provides. We will look at the following topics:

  • TCP protocol and different ports

  • TAP mode

  • OpenVPN secret keys

  • Routing

  • Complete setup, including IPv6

  • An IP-less setup...