Virtual Hosting with vsftpd + TLS encryption and MySQL on Ubuntu 15.10

Vsftpd is one of the most secure and fastest FTP servers for Linux. Usually, vsftpd is configured to work with system users. This document describes how to install a vsftpd server that uses virtual users from a MySQL database instead of real system users. This is much more performant and allows to have thousands of ftp users on a single machine.