Table of Contents

Chapter 1 looks at what VPNs are, how they evolved during the last decade, why it is necessary to modern enterprises, how typical VPNs work. The chapter also covers some essential networking concepts. Chapter 2 explains VPN security issues, including symmetric and asymmetric encryption, the SSL/TLS library, and SSL certificates. Chapter 3 introduces OpenVPN. In this chapter, we learn about the history of OpenVPN, how OpenVPN works, and how OpenVPN compares to IPSec VPN applications. Chapter 4 covers installing OpenVPN on both Windows, the Mac, Linux, and FreeBSD. It covers the installation on Linux from the source code and RPM packages. Installation on Suse and Debian is covered in detail. In Chapter 5, an encryption key for OpenVPN is created and it is then used to setup our first OpenVPN Tunnel between two windows systems in the same network. The key is then copied on a Linux system and this system is connected through tunnel to the first windows machine. Chapter 6 shows how to create x509 server and client certificates for use with OpenVPN. easy-rsa which comes with OpenVPN and is available for both Windows and Linux is used. Chapter 7 reviews the syntax of the command line tool openvpn, which enables building tunnels quickly. The configuration options of openvpn are covered in detail with examples. Chapter 8 shows how to make the example tunnels created earlier safer and persistent by choosing a reliable combination of configuration file parameters. It then covers how to configure firewalls on Linux and Windows to work with OpenVPN. Chapter 9 focuses on using xca, the advanced Windows tool with which x509 certificates can be easily managed. Its Linux equivalent, Tinyca2, which can even manage multiple certificate authorities, is also covered. Chapter 10 covers advanced OpenVPN configurations, including Tunneling through a proxy server, pushing routing commands to clients, pushing and setting the default route through a tunnel, Distributed compilation through VPN tunnels with distcc, and OpenVPN scripting. Chapter 11 shows how to debug and monitor VPN tunnels. It covers standard networking tools that can be used for scanning and testing the connectivity of a VPN server.

About the Author

Markus Feilner is a Linux professional from Regensburg, Germany, and has been working with open-source software since the mid 1990s. His first contact with UNIX was a SUN cluster and SPARC workstations at Regensburg University (during his studies of geography). Since the year 2000, he has published several documents used in Linux training all over Germany. In 2001, he founded his own Linux consulting and training company, Feilner IT. He was working as a trainer, consultant, and systems engineer at Millenux, Munich, where he focused on groupware, collaboration, and virtualization with Linux-based systems and networks. Since 2007, he is an editor at the German Linux-Magazine, where he is writing about Open-Source-Software for both printed and online magazines, including the Linux Technical Review and the Linux Magazine International www.linux-magazine.com. He regularly holds speeches and lectures at conferences in Germany. He is interested in anything about geography, traveling, photography, philosophy (especially that of open-source software), global politics, soccer and literature, but always has too little time for these hobbies. Markus Feilner supports Linux4afrika - a project bringing Linux computers into African schools. For more information please visit www.linux4afrika.de!