At first, point-to-point mode using pre-shared keys was the only available option when using OpenVPN. Nowadays, there are multiple ways to use OpenVPN, but point-to-point mode still has its uses. The term point-to-point mode using pre-shared keys is often abbreviated to pre-shared keys.
In point-to-point mode, OpenVPN is configured using pre-shared secret keys for predefined endpoints, and only a single endpoint can connect to a server instance at a time. The term server can be considered misleading, as both endpoints are more or less equal when it comes to functionality. The endpoint that initiates the connection is considered the client, the other endpoint is considered as the server.
We will start off with a demonstration of a very basic example. After that, we will discuss more features that OpenVPN provides. We will look at the following topics:
TCP protocol and different ports
OpenVPN secret keys
Complete setup, including IPv6
An IP-less setup...