SFTP Server service

Is there a SFTP service available to run on OL Connect workflow?
This would be the service you would login to, not a client to output to or retrieve files with.

Has to be SFTP and not FTPS.

If not any ideas on what to use?
IIS only supports FTPS and not SFTP.

I would look at WinSCP. It is a reputable organization, and the application is free.