RADIUS vs TACACS+: Understanding the Differences



What is the difference between RADIUS and TACACS+?



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RADIUS (Remote Authentication Dial-In User Service) and TACACS+ (Terminal Access Controller Access-Control System Plus) are two protocols used for AAA (Authentication, Authorization, and Accounting) in network devices like routers, switches, and firewalls.

The main difference between RADIUS and TACACS+ are as follows:

  1. Authentication and Authorization: TACACS+ separates the authentication and authorization functions, while RADIUS merges them. With TACACS+, the authentication process is performed first, and only after successful authentication, the authorization process takes place. In contrast, with RADIUS, the authentication and authorization happen simultaneously.

  2. Encryption: TACACS+ encrypts the entire payload, including the username, password, and the entire command set, while RADIUS encrypts only the password information. This means that TACACS+ provides better security than RADIUS.

  3. Command logging: RADIUS only logs the authentication attempts, while TACACS+ logs both the authentication attempts and the commands entered by the user. This means that TACACS+ provides better auditing capabilities than RADIUS.

  4. Type of Authentication: RADIUS is best suited for dial-up authentication, while TACACS+ can be used for various types of authentication, including dial-up, PPP, and network access.

Overall, TACACS+ is considered to be a more secure and flexible protocol than RADIUS, as it provides separate authentication and authorization processes, full payload encryption, and command logging. However, RADIUS is still widely used because of its simplicity and compatibility with a wide range of devices.