`authy-ssh` is much more advanced, but costs if you want over 3 authentications per day: <a href="https:&#x2F;&#x2F;www.authy.com&#x2F;product&#x2F;pricing&#x2F;" rel="nofollow">https:&#x2F;&#x2F;www.authy.com&#x2F;product&#x2F;pricing&#x2F;</a>