In this chapter, we started out by explaining what a VPN is. We then discussed some examples of different types of VPN protocols, including PPTP, IPSec, and OpenVPN. After a brief overview of the history of OpenVPN, we proceeded to dive deeper into the techniques used in OpenVPN. These techniques include the tun/tap adapter and the encryption and packet signing algorithms used.
After this introduction to VPNs and OpenVPN itself, it is now time to learn more about OpenVPN. In the next chapter, we will start with the most basic method of using OpenVPN, the point-to-point mode using pre-shared keys. As we progress throughout this book, you will gain a more in-depth knowledge of how to use OpenVPN in a wide variety of configurations.