Which protocol authenticates and authorizes users to services and accounts for their usage, typically using UDP ports 1812/1813?

Which protocol authenticates and authorizes users to services and accounts for their usage, typically using UDP ports 1812/1813?

• A. TACACS+
• B. HOTP
• C. TOTP
• D. RADIUS

Answer: (D)

RADIUS is the protocol designed for centralized authentication, authorization, and accounting in network access scenarios. It verifies a user’s identity when they try to reach a service and enforces what that user is allowed to do, while also logging usage for auditing. In practice, network devices like VPN gateways or wireless access points forward credentials to a RADIUS server, which checks them and responds with the permitted access. The telltale detail is its use of UDP ports 1812 for authentication and 1813 for accounting, which is how it handles both who you are and what you’re allowed to do, along with keeping usage records. HOTP and TOTP are methods for generating one-time passwords, not network access control protocols. TACACS+ is another AAA protocol but it’s primarily used for device administration and typically runs over TCP, not UDP ports 1812/1813.

RADIUS is the protocol designed for centralized authentication, authorization, and accounting in network access scenarios. It verifies a user’s identity when they try to reach a service and enforces what that user is allowed to do, while also logging usage for auditing. In practice, network devices like VPN gateways or wireless access points forward credentials to a RADIUS server, which checks them and responds with the permitted access. The telltale detail is its use of UDP ports 1812 for authentication and 1813 for accounting, which is how it handles both who you are and what you’re allowed to do, along with keeping usage records.

HOTP and TOTP are methods for generating one-time passwords, not network access control protocols. TACACS+ is another AAA protocol but it’s primarily used for device administration and typically runs over TCP, not UDP ports 1812/1813.