How to install ProFTPd with TLS support on Ubuntu 16.04

This tutorial shows how to install and use FTP with ProFTPd securely. FTP without TLS is an insecure protocol because all passwords and all data are transferred in clear text. By using TLS, the whole communication can be encrypted, thus making FTP much more secure. This article explains how to set up ProFTPd with TLS on an Ubuntu 16.04 server, how to add an FTP user and to use FileZilla to connect securely with TLS.