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

Pros and cons of the key mode

The main use case for using pre-shared key mode is to connect two remote networks, for example, a main office and a remote office of a small company. As soon as more than three users or endpoints are required, it is far easier to use client/server mode, as described in Chapter 4, Client/Server Mode with tun Devices. An example of how to connect three sites together using pre-shared keys is given later in this chapter, and it will become clear why pre-shared key mode does not scale well beyond three sites or users.

The main advantages of using pre-shared key mode are as follows:

  • It is very easy to set up

  • There is no need for public key infrastructure (PKI) or X.509 certificates

  • Can run on limited hardware, such as Linux-based switches or routers

The disadvantages of using pre-shared key mode are:

  • As the name point-to-point indicates, only two endpoints can be used by a single connection. Therefore, this mode does not scale well.

  • Some GUI wrappers for OpenVPN (for example...