Using FTP protocol is probably the easiest way to transfer files between a server and client computers…. anyone can simply download an FTP client and begin transfering files… however, it is inherently insecure in its standard form…
Now a more secure way to use FTP is via FTP over SSH or SFTP… If you unable to configure SFTP, then the closest thing will be to enable SSL/TLS certificates with your setup or FTPS
This post shows students and new users how to install and configure Pure-FTPD to use SSL/TLS certificates on Ubuntu 16.04 / 17.10 or 18.04 LTS server with encryption enabled..
The reason you may want SSL/TLS enabled on FTP is that FTP communicates over insecure channel… and someone with the right tool could intercept data between the server and client read it. With SSL/TLS, even if the data is intercepted, they may still be unable to read the content, and that’s because of the extra security.
For this post, we’re going to be using a self-signed certificate… If you can afford public cert, then more power to you..