Is there any inexpensive (preferably free) software that will let me expose an old insecure FTP server as if it were a secure FTPS server? Given that the protocol is FTP, it's a little more tricky than HTTP because new FTP uses multiple ports and commands had to be added to switch from FTP to FTPS. This would seem to be something that would have broad interest, but after 3 hours on google, I've been unable to find any such software.
In my case, I can't just use an off-the-shelf FTPS server because the FTP server I'm using doesn't store the files locally--it's just a virtual FTP server that presents an FTP view of yet another backend service.
Note that by FTPS I mean FTP over SSL (RFC 4217), not SFTP (which is a completely different protocol).