poc | server | client | server-2fa | client-2fa
see server-2fa
vi /etc/openvpn/client.conf # google authenticator auth-user-pass auth-nocache
==> here you simply need to use the TOTP instead of password
vi /etc/openvpn/client.conf # google authenticator auth-user-pass auth-nocache reneg-sec 0 static-challenge pin? 1
openvpn --config client.conf
note client certificate is independent from user auth and TOTP – you can easily mix the one with the other for quick testing