Remote Authentication Dial-in User Service (RADIUS) Federation

Remote Authentication Dial-In User Service (RADIUS) Federation is a method of extending RADIUS authentication and authorization services across multiple administrative domains or organizations. It allows different network access servers (NAS) to share user authentication and authorization information with a centralized RADIUS server, enabling a unified and secure authentication process for users across multiple networks.

In traditional RADIUS setups, each NAS (e.g., wireless access points, VPN servers, etc.) has its own local RADIUS server responsible for authenticating and authorizing users. However, in scenarios where users need to access multiple networks managed by different organizations or service providers, RADIUS Federation comes into play.

RADIUS Federation involves the following components:

  1. Home RADIUS Server: This is the centralized RADIUS server located in the user's home domain or organization. It holds the user's authentication credentials and authorization policies.
  2. Visited Network: This is the network to which the user is trying to connect. It hosts the NAS and relies on the user's home RADIUS server for authentication and authorization through the federation process.
  3. Federation Trust Relationship: A trust relationship is established between the home RADIUS server and the visited network's RADIUS server. This trust enables the visited network's RADIUS server to forward authentication requests to the user's home RADIUS server for validation.
  4. RADIUS Proxying: When a user attempts to connect to a network within the visited domain, the NAS sends the authentication request to its local RADIUS server. The local server acts as a proxy and forwards the request to the user's home RADIUS server for authentication.
  5. Authentication and Authorization: The user's home RADIUS server validates the user's credentials and applies the relevant authorization policies. The response is then sent back through the trust relationship to the visited network's RADIUS server, which communicates the result to the NAS.
  6. Access Grant or Denial: Based on the response from the home RADIUS server, the NAS either grants the user access to the network or denies access if the authentication is not successful.

RADIUS Federation is valuable in scenarios where roaming users need to access multiple networks without having to manage separate credentials for each network. It promotes centralized authentication, simplifies user management, and enhances security by maintaining authentication data within the home domain.