Overview
This lecture explains the RADIUS protocol, its purpose in network authentication, and the general process of authenticating users through RADIUS.
RADIUS Protocol Overview
- RADIUS (Remote Authentication Dial-in User Service) is a protocol providing AAA (Authentication, Authorization, Accounting) services.
- It is commonly used for managing access to internal networks, Wi-Fi, email, and VPN services.
- Initially created for remote dial-up user authentication, RADIUS now supports protocols like EAP (Extensible Authentication Protocol).
RADIUS Authentication Process
- Users do not interact directly with the RADIUS server when authenticating.
- Clients present credentials to a Network Access Server (NAS), which relays this information to the RADIUS server.
- The RADIUS server verifies the credentials using its configured authentication method.
RADIUS Server Verification Methods
- RADIUS servers can authenticate users using information stored in flat files.
- They can integrate with external sources like SQL databases, LDAP, Kerberos, or Active Directory.
RADIUS Server Responses
- After evaluating credentials, the RADIUS server responds with one of three messages:
- Access Reject (authentication failed)
- Access Challenge (further input required)
- Access Accept (authentication successful)
Key Terms & Definitions
- RADIUS — Protocol providing centralized Authentication, Authorization, and Accounting services for network access.
- AAA — Authentication, Authorization, Accounting; three functions to control and track network access.
- NAS (Network Access Server) — Device that mediates user connections and forwards authentication requests to the RADIUS server.
- EAP (Extensible Authentication Protocol) — Framework supporting multiple authentication methods with RADIUS.
- Access Reject — RADIUS response indicating failed authentication.
- Access Challenge — RADIUS response requesting more authentication information.
- Access Accept — RADIUS response indicating successful authentication.
Action Items / Next Steps
- Review how RADIUS integrates with directory services like LDAP or Active Directory.
- Prepare to troubleshoot authentication issues involving NAS and RADIUS communication.