How To Set Up OpenVPN To Authenticate With LinOTP

How To Set Up OpenVPN To Authenticate With LinOTP
This howto will show you the way to set up OpenVPN to authenticate users
against the LinOTP authentication backend. Thus you can bring up your
VPN using two factor authentication with different kind of OTP tokens. The interesting part is, that we will also use client certificates, so
that the VPN only gets established if the machine has the right client
certificate and the user has the right OTP token.