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
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Client-side routing


Sometimes, it is useful to allow the VPN server (or other VPN clients) to access resources connected to a particular client. This is known as client-side routing. Client-side routing in OpenVPN requires a CCD file for that client containing an iroute statement. It also requires a corresponding route statement in the OpenVPN server configuration file.

Consider the following network layout:

The subnet 192.168.4.0/24 needs to be accessible from the server-side LAN and the server-side subnet 192.168.122.0/24 needs to be accessible from the client-side LAN. This can be achieved as follows:

  1. Add two lines to the basic-udp-server.conf configuration file:

    client-config-dir /etc/openvpn/movpn/clients
    route 192.168.4.0 255.255.255.0 10.200.0.1

    Save it as movpn-04-05-server.conf.

  2. Create a CCD file client1 in the directory /etc/openvpn/movpn/clients with contents:

    ifconfig-push 10.200.0.99 255.255.255.0
    iroute 192.168.4.0 255.255.255.0
    push “route 192.168.122.0 255.255.255.0”
  3. Ensure that...