This recipe uses OpenVPN secret keys to secure the VPN tunnel. It is very similar to the previous recipe, but this time, we will use a shared secret key to encrypt the traffic between the client and the server.
Install OpenVPN 2.3.9 or higher on two computers. Make sure the computers are connected over a network. For this recipe, the server computer was running CentOS 6 Linux and OpenVPN 2.3.9 and the client was running Windows 7 64 bit and OpenVPN 2.3.10.
[root@server]# openvpn --genkey --secret secret.key