RADIUS Remote Authentication DialIn User Service 🌐

Overview of RADIUS 📡

RADIUS is a protocol that provides Authentication, Authorization, and Accounting (AAA) services for users on a network. It is widely used to manage access to internal networks, WiFi networks, email services, and VPN services.

• History: Originally designed for transporting authentication information for remote dial-up users, RADIUS has evolved to support various standard authentication protocols, including Extensible Authentication Protocol (EAP).

Role of RADIUS in Authentication 🔐

• Client Interaction: Clients do not interact directly with the RADIUS server. Instead, they present their authentication credentials to a Network Access Server (NAS) or similar device.

• Credential Relay: The NAS relays these credentials to the RADIUS server for verification.

• Authentication Scheme: The RADIUS server verifies the credentials using a configured authentication scheme, which could involve flat files or external sources like SQL databases, LDAP, Kerberos, or Active Directory.

RADIUS Authentication Process ✅

1. Credential Submission: A client submits authentication credentials to the NAS.

2. Relay to RADIUS: The NAS forwards these credentials to the RADIUS server.

3. Verification: The RADIUS server checks the credentials against its authentication scheme.

4. Response: Based on the verification, the RADIUS server responds with one of the following messages:

   • Access-Accept: Credentials are valid; access is granted.

   • Access-Reject: Credentials are invalid; access is denied.

   • Access-Challenge: Further information or verification is required.

Key Points for IT Support Specialists 🛠️

• Understanding RADIUS: Even if you're not configuring RADIUS servers directly, knowing how RADIUS works can help troubleshoot issues when clients authenticate against RADIUS backend servers.

• Common Use Cases: RADIUS is used for managing access to a variety of network services, making it essential knowledge for handling network security and user authentication issues.

Key Takeaways 📌

1. Protocol Function: Provides AAA services for network access.

2. Client Interaction: Involves credential submission via NAS, not direct server interaction.

3. Verification Sources: Can use internal or external authentication sources.

4. Server Responses: Includes Access-Accept, Access-Reject, and Access-Challenge.

Understanding RADIUS helps in managing and troubleshooting network authentication effectively.