View source for Remote Authentication Dial-In User Service

== Remote Authentication Dial-In User Service (RADIUS) ==

The '''Remote Authentication Dial-In User Service''' (RADIUS) is a networking protocol that provides centralized authentication, authorization, and accounting (AAA) management for users who connect and use a network service, such as dial-up, VPN, or wireless network. RADIUS allows a company to maintain user profiles in a central database and authenticate users before granting them access to network resources.

=== Operation ===

RADIUS operates on a client-server model and involves the following key components:

* '''RADIUS Client''': A device or software application that forwards authentication requests from users to the RADIUS server for processing. RADIUS clients include network access servers, such as routers, switches, VPN gateways, and wireless access points.
* '''RADIUS Server''': A centralized server that authenticates users, authorizes their access to network resources based on predefined policies, and maintains accounting records for billing and auditing purposes.
* '''User Database''': The user database stores user profiles, including usernames, passwords, access privileges, and accounting information. RADIUS servers authenticate users by verifying their credentials against the user database.
* '''AAA Transactions''': RADIUS transactions involve three phases: Authentication, Authorization, and Accounting. During authentication, the RADIUS server verifies the user's credentials. Upon successful authentication, the server checks the user's authorization level to determine access privileges. Finally, the server logs accounting information, such as session duration and data usage, for billing and auditing purposes.

=== Features ===

RADIUS provides several features that make it suitable for network authentication and access control:

* '''Centralized Management''': RADIUS enables organizations to centrally manage user authentication and access control policies, ensuring consistent enforcement across distributed networks.
* '''Scalability''': RADIUS is designed to scale to accommodate large numbers of users and network access devices, making it suitable for enterprise deployments.
* '''Authentication Methods''': RADIUS supports various authentication methods, including Password Authentication Protocol (PAP), Challenge Handshake Authentication Protocol (CHAP), and Extensible Authentication Protocol (EAP), allowing organizations to choose the most appropriate method for their security requirements.
* '''Accounting Support''': RADIUS maintains detailed accounting records of user sessions, including login and logout times, data transferred, and services accessed, enabling organizations to track usage and enforce billing policies.

=== Applications ===

RADIUS is used in various networking environments and applications, including:

* '''Wireless Networking''': RADIUS is commonly used in wireless LAN (WLAN) deployments to authenticate users and enforce access control policies for Wi-Fi access points.
* '''Remote Access''': RADIUS is used in remote access solutions, such as Virtual Private Network (VPN) and dial-up connections, to authenticate users and control their access to corporate networks.
* '''Network Access Control''': RADIUS is used in network access control (NAC) solutions to authenticate and authorize devices before granting them access to network resources.

=== Advantages ===

* '''Centralized Authentication''': RADIUS centralizes user authentication and access control, simplifying management and ensuring consistent enforcement of security policies.
* '''Scalability''': RADIUS is scalable and can support large numbers of users and network devices, making it suitable for enterprise-scale deployments.
* '''Interoperability''': RADIUS is an industry-standard protocol supported by a wide range of networking equipment and software vendors, ensuring interoperability across different platforms and devices.

=== Disadvantages ===

* '''Complexity''': Setting up and configuring RADIUS servers and clients can be complex, requiring knowledge of networking and security concepts.
* '''Single Point of Failure''': RADIUS servers can become a single point of failure in the network if they are not properly redundant and failover mechanisms are not implemented.

== See Also ==
* [[Authentication|Authentication]]
* [[Authorization|Authorization]]
* [[Accounting|Accounting]]
* [[EAP|Extensible Authentication Protocol (EAP)]]
* [[VPN|Virtual Private Network (VPN)]]

== References ==
* [https://tools.ietf.org/html/rfc2865 RFC 2865 - Remote Authentication Dial In User Service (RADIUS)]

[[Category:Protocols]]