What is TACACS/Radius?

TACACS+ (Terminal Access Controller Access-Control System Plus) and RADIUS (Remote Authentication Dial-In User Service) are network protocols used for centralized Authentication, Authorization, and Accounting (AAA). They are commonly used to manage user access to network devices and resources. TACACS+ is Cisco's proprietary protocol, using TCP port 49, and encrypts the entire packet body, while RADIUS is an open standard protocol, often using UDP ports 1812/1813 or 1645/1646, and only encrypts the password. TACACS+ offers more granular authorization and accounting features, making it suitable for device administration, while RADIUS is widely used for network access control, such as authenticating users connecting to a wireless network or VPN.