New port: security/duo_openvpn:

Duo provides simple two-factor authentication as a service via:

1. Phone callback
2. SMS-delivered one-time passcodes
3. Duo mobile app to generate one-time passcodes
4. Duo mobile app for smartphone push authentication
5. Duo hardware token to generate one-time passcodes

Duo two-factor authentication for OpenVPN

WWW: https://github.com/duosecurity/duo_openvpn