RADIUS

Extension	Port	Introduction
Change of Authorization (CoA)	UDP 1700	Allow dynamically modify an active user or device's session permissions (e.g., VLAN, bandwidth, access level) in real-time without requiring re-authentication.

Application of RADIUS

Feature	Windows (NPS)	Linux (FreeRADIUS)
Platform	Windows Server only	Most Linux distributions
GUI	Yes	No (CLI + config files)
AD Integration	Native	Possible (requires setup)
Customizability	Limited	Very high
Resource Usage	Moderate to high	Lightweight
Licensing	Requires Windows Server license	Free (open-source)
Use Case Fit	Enterprise with AD	ISP, universities, cloud, etc.

Configuration Example