The JUNOS software supports three methods of user authentication: local password authentication, Remote Authentication Dial-In User Service (RADIUS), and Terminal Access Controller Access Control System Plus (TACACS+).
With local password authentication, you configure a password for each user allowed to log into the Services Router.
RADIUS and TACACS+ are authentication methods for validating users who attempt to access the router using Telnet. Both are distributed client/server systems—the RADIUS and TACACS+ clients run on the router, and the server runs on a remote network system.
You can configure the router to use RADIUS or TACACS+ authentication, or both, to validate users who attempt to access the router. If you set up both authentication methods, you also can configure which the router will try first.