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

Using LDAP as a backend authentication mechanism

Normally, the security of a VPN is based on a X.509 certificate / private key pair, which all users of the VPN must possess in order to gain access. The security of your VPN can be further increased by requiring users to also supply a username and password when they connect to the OpenVPN server.

On the server side, the verification of the username and password can be done using several mechanisms:

  • Using a server-side password file that contains the username and their hashed passwords.

  • Using PAM (short for Pluggable Authentication Module), which is normally included in all Linux/UNIX operating systems.

  • Using a central directory server based on Lightweight Directory Access Protocol (LDAP). Note that both LDAP and Active Directory can be used with various PAM modules as well.

It is also possible to authenticate against a Windows Active Directory domain, as this is very similar to using a standalone LDAP server. In this example, we will show you...