I am writing an FTP server using the Python framework Twisted. Twisted has its own plain FTP implementation – but it doesn’t support FTPS. I’ve noticed that most clients connect and immediately issue an AUTH TLS command, requesting an encrypted FTPS connection. If the server responds that this command is not supported, they just disconnect.

There are third-party libraries that implement explicit FTPS server (i.e., the client connects via FTPS right off the bat) like this one – but this is not what I need. I need implicit FTPS support – i.e., to switch to a TLS connection from within an FTP connection when the AUTH TLS command is received.

Any ideas how to do this?