Install and Configure FreeRADIUS on Ubuntu 18.04 with MySQL

FreeRADIUS is an authentification, authorization and accounting protocol. It was built in the dial-up era to manage users and keep track of the bandwidth usage by each connection for billing purposes. It is still a very strong tool to use even today. It is fast to set up and many networking programs like OpenVPN, SotfEther, Squid proxy and WiFi managing tools can be integrated with FreeRADIUS.