If you need to connect your network devices in your IT system, RADIUS (Remote Authentication Dial-In User Service) will help you to get AAA capabilities — Authentication, Authorization, and Accounting. I will show how to use RADIUS services on a Windows Server 2019. I will skip some installation parts, since you can find them on the internet and reference section, below. In this topology, there is a switch needs to be reached by an administrator using username and password. By using any RADIUS server, all authentication can be done easily and more securely. Once an administrator changes admin password, all registered devices can be accessible using a RADIUS server easily.