These instructions describe setting up two-factor authentication with WiKID Strong Authentication, which is a commercial/open source two-factor authentication system and OpenVPN, an SSL-encrypted VPN, on an Ubuntu 13.04 Linux server using the Radius Pluggable Authentication Module. First, we will configure PAM to use Radius, then we will configure OpenVPN to use PAM and one-time passwords, then we will create a network client on the WiKID server for OpenVPN. We won’t go into specifics about installing these services, rather we will focus on configuring them to all work together.