Currently using Radmin, but this is a not a sufficient form or a 2 factor authentication against our servers. Options I am currently investigating would be 1) VPN, 2) Purchasing Certificates 3) Setting up a Certificate Server. Want to deploy the most cost effective means to ensure we have indeed a 2 factor authentication for remote admin. Any suggestions or other tools/methods would be more than welcome. Keeping in mind these machines are all standalone and not on any domain at this time.