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

Advanced configuration options

The next few sections illustrate some advanced configuration options. It is suggested you fully understands the impact to their network before deploying these in a production environment. These options are rarely used, but can be extremely beneficial in the right circumstances.

Proxy ARP

It is often desirable to make VPN clients appear as if they are part of the server-side network. This makes it easier to browse folders and share files and printers. To achieve this purpose, many setups resort to Ethernet bridging (see Chapter 6, Client/Server Mode with tap Devices), which has its own drawbacks. The performance of a bridged configuration can be much lower compared to a nonbridged setup.

When the OpenVPN server runs on Linux or Unix, there is an alternative solution: most Unix kernels have Proxy ARP capabilities, which can be used to assign an OpenVPN client with an IP address on the server-side LAN, and make it appear as if it is part of that LAN. Note that this...