I&#x27;ve been using Duo Security to add 2FA on SSH and other services on my SmartOS instances.  It&#x27;s really easy and the price is pretty low compared to the amount of work it would take to manage the keys and manual implementations.<p>In theory I could worry about Duo going down, but I also rely on other critical cloud services and do have other ways to access an instance in an emergency (and Duo supports fallbacks).<p>Simplicity can be deceiving. In this case I think leaving security to the pros is worth the tradeoff.  I&#x27;ve previously relied on cloud services for secure user management and wasn&#x27;t let down.