I'm wondering if there's any existing FTP proxy product that supports FTP-SSL/TLS that can be used under Linux Redhat environment.
There is a tlswrap however looks like it's been out of maintenance for years.
Actually, I've just finished adding FTPS support to a mod_proxy module for proftpd; it can handle FTPS on the frontend (from clients) and on the backend (to servers), in both forward and reverse proxy modes; see mod_proxy.
Full disclaimer: I'm the author of mod_proxy
and ProFTPD.