Remote Authentication Dial-in User Service (RADIUS)
Remote Authentication Dial-In User Service (RADIUS) is a networking protocol widely used in identity and access management to secure authentication, authorisation, and accounting (AAA) for network access. Originally developed to facilitate remote access to dial-in networks, RADIUS is now commonly used across Wi-Fi networks, virtual private networks (VPNs), and other types of secure networks, providing a centralised approach to managing user authentication and access control.
In practice, RADIUS works by enabling client devices to communicate with a centralised authentication server to verify a user’s identity before granting access to the network. When a user attempts to connect to a network, the device sends a request to the RADIUS client, typically integrated within a network access server (NAS) or similar infrastructure. The RADIUS client then forwards the request to the central RADIUS server, which verifies the credentials, applies appropriate access policies, and returns a response. This approach not only simplifies authentication management by centralising user credentials but also allows organisations to enforce consistent access policies across various entry points, whether they are Wi-Fi hotspots, VPNs, or enterprise networks.
One of the strengths of RADIUS in cybersecurity is its support for multi-factor authentication (MFA), which adds an extra layer of protection to standard password-based access. As cyber threats have grown more sophisticated, many organisations have incorporated MFA into their RADIUS setup, prompting users to provide additional proof of identity, such as a one-time passcode, in addition to a password. This multi-factor approach significantly reduces the risk of unauthorised access, especially in environments where network access points are shared or public.
RADIUS also supports robust authorisation capabilities, allowing network administrators to assign specific access levels and restrictions based on user roles. For instance, administrators can define policies that limit certain users to specific resources or set time-based restrictions for network access, providing a highly granular level of control. In environments such as large enterprises or educational institutions, this is invaluable for managing diverse user groups, such as employees, contractors, and students, each with different access needs. By defining these policies centrally, administrators can ensure that security standards are uniformly applied across the network, minimising the risk of privilege misuse or unauthorised access to sensitive areas.
In addition to authentication and authorisation, RADIUS is integral to accounting, tracking user activities and network access over time. By logging details such as session durations, bandwidth usage, and access times, RADIUS helps organisations maintain an auditable trail of network activity, which is crucial for both compliance and incident response. In the event of a security breach, RADIUS logs can provide valuable insights into user behaviour and access patterns, assisting security teams in identifying potential vulnerabilities or sources of unauthorised access.
