300-715 practice question 19 of 35

Which are two characteristics of TACACS+? (Choose two)

Full set: 294 questions

Answer options

A: It uses TCP port 49. Correct answer

B: It combines authorization and authentication functions.

C: It separates authorization and authentication functions. Correct answer

D: It encrypts the password only.

E: It uses UDP port 49.

Correct Answer:

A. It uses TCP port 49.; C. It separates authorization and authentication functions.

Explanation

Terminal Access Controller Access-Control System Plus (TACACS+) is a security protocol that provides centralized validation for network access. A key architectural feature of TACACS+ is the explicit separation of Authentication, Authorization, and Accounting (AAA) functions. This modularity allows for different servers or processes to handle each function, offering greater flexibility and control. For transport, TACACS+ uses the Transmission Control Protocol (TCP) on port 49. The use of TCP ensures a reliable, connection-oriented session between the client (Network Access Server) and the TACACS+ server for the exchange of AAA messages.

Why Incorrect

B. TACACS+ explicitly separates authentication and authorization functions. Combining them is a characteristic of the RADIUS protocol.
D. TACACS+ encrypts the entire body of the packet, providing more comprehensive confidentiality than RADIUS, which only encrypts the password.
E. TACACS+ uses the connection-oriented TCP protocol for reliable communication, not the connectionless UDP protocol.

References

1. Cisco. (2023). Cisco Identity Services Engine Administrator Guide, Release 3.2. "Device Administration with TACACS+." "TACACS+ is a security protocol that provides centralized validation of users who are attempting to gain access to a router or network access server. TACACS+ provides separate authentication, authorization, and accounting (AAA) services... TACACS+ uses TCP port 49."

2. De Cnodder, S., & Carugi, M. (2020). The TACACS+ Protocol, draft-ietf-opsawg-tacacs-14. Internet Engineering Task Force (IETF). Section 1.1, "TACACS+ is a TCP-based protocol that provides for separate Authentication, Authorization, and Accounting (AAA) services."

3. De Cnodder, S., & Carugi, M. (2020). The TACACS+ Protocol, draft-ietf-opsawg-tacacs-14. Internet Engineering Task Force (IETF). Section 8.1, "IANA has assigned TCP port 49 as the well-known port for TACACS+."

4. Cisco. (2018). TACACS+ and RADIUS Comparison. "TACACS+ uses Transmission Control Protocol (TCP) on port 49." and "TACACS+ encrypts the entire body of the packet but leaves a standard TACACS+ header."

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