What are RADIUS Authentication Methods / Protocols Used

What are RADIUS Authentication Methods / Protocols Used. This blog delves into the RADIUS protocol, its authentication methods, and how it works to provide secure access control to network resources.

With the rise of remote access and wireless networking, secure authentication and authorization have become critical for ensuring network security. Hence, RADIUS – an authentication protocol, designed to provide accounting, and centralization for accessing networks. Commonly used by service providers and large organizations to manage user authentication for remote access connections.

What are RADIUS Authentication Protocol?

RADIUS (Remote Authentication Dial In User Service) is an authentication protocol. Provides secure authentication and user management for remote access connections, such as VPNs, wireless networks, and dial up connections.

Benefits of RADIUS Authentication

Centralized Management

One of the most significant benefits of using RADIUS for wireless authentication is centralized management. With RADIUS, managing user accounts and ensuring consistent access across multiple access points becomes a breeze.

Increased Security

Another significant advantage of using RADIUS for wireless authentication is better security. With the help of RADIUS, authentication and encryption methods (EAP TLS and EAP TTLS) are more reliable, and secure, and provide one of the best security for sensitive information. Moreover, RADIUS offers a safe encryption technique compared to commonly used wireless authentication methods like WEP, WPA, or WPA2.

Better Scalability

As businesses grow, so does the need for more access points to accommodate more users. So, Radius authentication provides better scalability for wireless networks as it handles a large number of users and access points without compromising security or performance.

Audit Trail and Reporting

Gives detailed logging and reporting, which is critical in compliance and regulatory environments. It allows network administrators to track user activity, identify security breaches, and generate usage reports.

Ease of Integration

Businesses seamlessly integrate RADIUS authentication with their existing authentication methods like LDAP, Active Directory, or Kerberos. This helps simplify the authentication process and avoids any extra burden on users. The integration also enables businesses to leverage their existing authentication infrastructure, reducing costs and increasing efficiency.

How RADIUS Authentication Works?

Well, Radius servers are commonly used for Virtual Private Networks (VPNs, wireless networks) along with other remote access scenarios.

  • If you try to access a network secured by Radius, the server asks for your credentials “username and password”. The server then verifies your identity by comparing it against an unauthorized user database. Once it verifies your credentials, it allows you to access the server.
  • Moreover, RADIUS servers provide additional features beyond authentication, including accounting and authorization. On one hand, the accounting enables the collection and recording of usage data for each user, allowing for detailed monitoring and reporting. Meanwhile, authorization offers precise control over network resources and user actions, granting access only to authorized users and limiting their access as needed.
  • Overall, Radius servers play a vital role in securing networks, providing robust authentication and authorization mechanisms to safeguard against potential security threats.

RADIUS Authentication Protocols

The RADIUS utilizes different authentication techniques, such as PAP, CHAP, MS CHAP, and EAP. This allows for flexibility in choosing the most suitable method for the specific network environment and security requirements. Each authentication method offers a different level of security and usability.

Password Authentication Protocol (PAP)

PAP is the simplest authentication method that RADIUS uses. The password is sent in plain text over the network, which leaves it open to eavesdropping and sniffing attacks. For this reason, PAP is not a good option for secure networks.

Challenge Handshake Authentication Protocol (CHAP)

The CHAP authentication method involves a three step process to verify and authorize users, which results in the creation of a unique session key. This makes it a more secure way of authentication compared to PAP. The server sends a challenge message to the client, which response with a hashed value that includes the user’s password and the challenge message. Once the user sends the response, the server checks if it matches the expected value. If it does, the server allows access to the user.

Microsoft Challenge Handshake Authentication Protocol (MS CHAP)

MS CHAP is an enhanced version of CHAP that is often utilized in Microsoft environments. It provides more improvised features, including, password encryption, mutual authentication, etc. However, MS CHAP is vulnerable to dictionary attacks, where an attacker uses a pre computed hash to crack the password.

Extensible Authentication Protocol (EAP)

EAP is a flexible authentication framework, supporting multiple authentication methods (such as biometrics, Smart cards, and digital certificates). The common use of EAP is for wireless networks and VPNs, where users require strong authentication and encryption. EAP provides mutual authentication between the client and the server, which ensures that both parties are verified before establishing a connection.

Is RADIUS Protocol UDP or TCP?

The RADIUS server and the NAS use two different protocols named User Datagram Protocol (UDP) and Transmission Control Protocol (TCP) for communication.

  • UDP is a lightweight, connectionless protocol, and doesn’t require a connection to be established before data is sent.
  • TCP is a connection oriented protocol that establishes a connection before data has been sent. For RADIUS, UDP is used for faster authentication processing, but this might lead to reduced reliability because there is no guarantee that the data sent by the RADIUS server reaches NAS.
  • To address this, RADIUS includes a retry mechanism where the server retransmits the authentication request, if it doesn’t receive a response from the NAS within a specific timeframe.
  • The retry mechanism is an important aspect of the RADIUS authentication process. If the RADIUS server is not able to receive a response from the NAS within a specific timeframe, it retransmits the authentication request.
  • This ensures that the authentication process is reliable, even with the use of UDP. The retry mechanism is extremely important when it comes to managing a high volume of network traffic. Since it increases the probability of authentication requests being lost or delayed.

Types of RADIUS Authentication

Credential Authentication

The credential authentication method has been the most commonly used in RADIUS. The process consists of users providing their particular usernames and passwords to the RADIUS server. It is followed by verifying those credentials and granting or denying access based on the authentication results.

The RADIUS server stores its users’ credentials in a database or directory (Active Directory) and matches the credentials provided by the users with those already existing in the database.

If the credentials match, the RADIUS server sends an access accept message to the network access server (NAS), granting access to users for the network resources.

In case it does not match, the RADIUS server sends an access reject message to the NAS, denying access to the user.

Certificate Authentication

The certificate authentication method is a higher and more secure form of authentication compared to credential authentication. This method utilizes the use of digital certificates to verify the authentication of users.

In this process, the user’s device (Laptop, or smartphone) is equipped with digital certification to verify the identification. So, whenever users try to connect to the network, the Radius server instantly sends a certificate request to the users’ devices.

The device then sends its digital certificate to the RADIUS server for authentication.

Upon finding the valid digital certificate, and matches to the existing RADIUS server, the Radius server sends an access accept message to the NAS, allowing the users to access all the network resources.

But, if the certificate is invalid, and does not match, the RADIUS server denies the access and notify the NAS, which automatically denies the access to any user.

RADIUS Server Authentication and Authorization Working Mechanism

The RADIUS server is a highly effective tool for securely accessing a wide variety of network services, including wireless networks, VPNs, and remote desktop connections. Its strong access control mechanisms ensure that only authorized personnel accesses critical information and systems, making it an essential tool for businesses of all sizes. When accessing network resources, authentication plays a vital role in verifying a user’s identity.

  • Authentication verifies whether a user accesses resources or not. It verifies the authentication of the users to check the authorized credibility of the users. This whole process helps prevent unauthorized access and security breaches, safeguarding the network against infiltration.
  • Authorization is the process of determining which server a user may access to, once the authentication is complete. After the RADIUS server confirms the user’s identity, it sends an authorization message to the remote access server. This exchange is helping the server recognise the servers which are accessible by users. Depending on the user’s role or group membership, the RADIUS server allows different levels of access.
  • For authentication and authorization, the servers use a shared secret key to encrypt and decrypt messages. This exchange is only between the remote access server and the RADIUS server. This encryption technique makes it difficult for unauthorized users to intercept messages and access sensitive information.

How Secure is RADIUS?

RADIUS authentication is considered secure due to its use of encryption and the ability to integrate with various security protocols.

  • It is designed to provide secure authentication, authorization, and accounting services to networks. Unauthorized users cannot access the RADIUS as it asks for legit credentials. These credentials are further sent and verified by the RADIUS server.
  • The protocol is a security feature that uses encryption techniques to protect sensitive data, such as login credentials. It only employs reliable encryption protocols such as Secure Socket Layer to secure your login details and credentials.
  • RADIUS integrates with different security protocols including, PAP, CHAP, and EAP.
  • These protocols provide multiple layers of security. It enables mutual authentication between the client device and the RADIUS server, ensuring only authorized users access the network. By utilizing RADIUS, you are assured that your sensitive information is secure and safeguarded from unauthorized access.

Thank you for reading What are RADIUS Authentication Methods / Protocols Used. We shall conclude this article. 

What are RADIUS Authentication Methods / Protocols Used Conclusion

Finally, RADIUS is a protocol that helps to manage network access by providing centralized authentication, authorization, and accounting services. It’s a powerful tool for ensuring the security of network resources and controlling user access to them. It enables secure user management for remote access connections, such as VPNs, wireless networks, and dial up connections. By using RADIUS, organizations better control network access, manage user accounts and authentication policies, and track user activity on the network.

Avatar for Hitesh Jethva
Hitesh Jethva

I am a fan of open source technology and have more than 10 years of experience working with Linux and Open Source technologies. I am one of the Linux technical writers for Cloud Infrastructure Services.

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