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

Multiple CAs and CRLs

Easy-RSA 3.0 fairly easily supports multiple root CAs. By creating a separate CA directory under EASYRSA root, and having different vars files for each, each individual CA can be managed with Easy-RSA.

Currently, ssl-admin does not support multiple root CAs, but creation of intermediate CAs is supported.

With OpenVPN, a single server instance can support multiple root CAs, with client connections that have been signed by either CA being accepted. To enable such support, the CA certificate for each authorized CA needs to be concatenated together into a single file that can be called with the --ca OpenVPN option. The same can be done with the certificate revocation list.

Generally, it is not recommended to use multiple CA certificates for a single OpenVPN instance; exceptions could be server, or certificate authority migration, company or organization acquisitions, and so on.

Under no circumstances would it be ideal to use a web browser root certificate authority for an OpenVPN...