RADIUS as a Service

What is RADIUS and how does it work?

What is RADIUS?

RADIUS stands for Remote Authentication Dial-In User Service. It is a protocol that provides centralized Authentication, Authorization, and Accounting (AAA) for users who connect and use a network service. It was originally developed for dial-up networks but is now widely used for managing access to wireless networks, VPNs, and network infrastructure devices like switches and firewalls.

How RADIUS Works

RADIUS functions using a client-server model and involves three main components:

• User Device: The end user’s device trying to access the network.
• RADIUS Client (Network Access Server – NAS): The device the user connects to, such as a Wi-Fi access point, switch, or VPN server. This acts as the client to the RADIUS server.
• RADIUS Server: The server that validates the user’s credentials and provides access decisions. It usually integrates with a backend identity database such as Active Directory, LDAP, or an internal user database.

Authentication Flow

• The user initiates a connection to the network via the NAS.
• The NAS prompts for credentials (e.g., username/password or certificate).
• These credentials are sent to the RADIUS server in an Access-Request message.
• The RADIUS server validates the credentials against its identity source.
• If the credentials are valid, the server sends an Access-Accept message. If not, it sends an Access-Reject.
• If access is granted, the NAS allows the user onto the network, potentially applying access policies returned by the RADIUS server.

Authorization

Beyond authentication, the RADIUS server can enforce specific access policies. These might include time-based access restrictions, VLAN assignments, or downloadable ACLs, depending on the user’s identity or role.

Accounting

RADIUS can also track and log user session data, such as session start and stop times, data usage, IP addresses, and session duration. This is used for auditing, usage tracking, and sometimes billing purposes.

Security Considerations

While RADIUS supports encrypting the password in the Access-Request packet, the rest of the packet, including attributes like username, is sent in plain text. To address this limitation, RADIUS is commonly used in conjunction with 802.1X and EAP (Extensible Authentication Protocol), which adds support for secure tunneling and certificate-based authentication, such as EAP-TLS.

Strengths of RADIUS

• Centralized control over network access.
• Scalable and widely supported across vendors.
• Compatible with various authentication methods, including credentials, certificates, and multi-factor authentication.

What is RADIUS as a service?

RADIUS as a Service refers to a cloud-based delivery model for the traditional RADIUS protocol. Instead of deploying and maintaining RADIUS servers on-premises, organizations subscribe to a managed RADIUS platform hosted and maintained by a third-party provider.

This model offers the same core functionality—Authentication, Authorization, and Accounting (AAA)—but without the operational overhead associated with deploying hardware, configuring high availability, performing updates, and securing the infrastructure.

How RADIUS as a Service Works

In this model, the cloud provider operates the RADIUS servers, which are distributed across multiple regions or data centers for reliability and scalability. Organizations configure their network devices (such as Wi-Fi controllers, VPN gateways, and firewalls) to point to the provider’s RADIUS endpoints.

When a user attempts to connect to the network, the access device (e.g., Wi-Fi AP or VPN server) forwards the user’s credentials to the RADIUS provider.

The cloud RADIUS service validates the credentials against an identity source, which might be:

• A cloud directory
• An on-premises directory via secure connector or agent
• A local user database within the provider’s platform

Upon successful authentication, the service returns access decisions and policy attributes (such as VLAN assignments or access controls) back to the access device.

Session details can also be recorded for auditing or accounting purposes.

Key Benefits of RADIUS as a Service:

• Reduced Infrastructure Burden: Eliminates the need for hosting, maintaining, and patching on-premises RADIUS servers.
• High Availability: Cloud providers typically offer built-in redundancy and global failover capabilities.
• Scalability: Can handle authentication requests from a large number of users and sites without performance degradation.
• Cloud Directory Integration: Often integrates natively with modern identity providers, enabling passwordless or certificate-based authentication.
• Zero Trust and NAC: Some services include context-aware policy enforcement, device posture checks, and integration with network access control systems.

Use Cases

• Enterprises with remote or hybrid workforces needing secure Wi-Fi or VPN access.
• Organizations transitioning to the cloud and decommissioning on-prem directory and AAA infrastructure.
• MSPs and IT teams managing network access across multiple branch offices without deploying physical servers.
• Environments adopting 802.1X authentication for wired and wireless networks.

Security Considerations

When using RADIUS as a Service, traffic between network devices and the cloud provider must be protected. This is usually done via IPsec tunnels or secure transport protocols. In addition, organizations should verify the provider’s data protection practices, regional compliance measures, and uptime guarantees.

In summary, RADIUS as a Service offers a modern, cloud-native approach to managing network access securely and efficiently, while removing much of the complexity of traditional RADIUS deployments.

What are the benefits of RADIUS as a service?

The benefits of RADIUS as a Service are primarily centered around simplification, scalability, and security. This cloud-based model eliminates the need for on-premises infrastructure and offers enhanced functionality that aligns with modern IT and security needs. Here are the key advantages:

1. Reduced Operational Overhead

RADIUS as a Service removes the need to deploy, maintain, and troubleshoot physical or virtual RADIUS servers. There’s no hardware to manage, no OS patching, and no need to build redundancy or failover systems manually. This results in significant time and cost savings for IT teams.

2. High Availability and Reliability

Most RADIUS-as-a-Service providers operate redundant infrastructure across multiple geographic locations. This means authentication services remain available even in the event of server or regional outages. Failover is automatic and transparent to end users.

3. Scalability

Cloud-based RADIUS platforms are designed to handle high volumes of authentication requests from distributed users and devices. As your organization grows or shifts to hybrid work, the service scales without requiring new hardware or additional licenses.

4. Seamless Integration with Cloud Identity Providers

Many providers offer direct integrations with cloud identity platforms. This simplifies user authentication workflows and supports features like multi-factor authentication (MFA), passwordless logins, and single sign-on (SSO).

5. Faster Deployment

Provisioning RADIUS in the cloud typically takes minutes, not days. There’s no need to procure servers or spend hours on complex configurations. Some providers even offer pre-built configuration templates for major network vendors like Cisco, Aruba, and Meraki.

6. Centralized Management Across Locations

Whether you have one site or hundreds, cloud RADIUS allows you to enforce consistent access policies from a single interface. This improves policy enforcement and simplifies compliance audits.

7. Enhanced Security Features

RADIUS as a Service often includes modern security enhancements:

• Support for secure EAP types (like EAP-TLS)
• Certificate-based authentication
• Device posture checks and contextual access control
• Encrypted communication tunnels between the access device and the RADIUS service

8. Improved User Experience

With features like persistent identity, policy caching, and identity-based VLAN assignment, users can roam between access points or sites without re-authenticating or experiencing connectivity drops.

9. Compliance and Reporting

Providers often include logging and reporting tools that assist with regulatory compliance, security investigations, and usage analytics. These features are typically available through dashboards or via integrations with SIEM tools.

10. Supports Zero Trust and Network Access Control (NAC)

Cloud RADIUS can be a foundational component of Zero Trust architecture. It enables context-aware access policies based on identity, device, location, and time. When combined with NAC solutions, it ensures only authorized and compliant devices can access sensitive network segments.

Who should use RADIUS as a service?

RADIUS as a Service is ideal for organizations seeking to modernize their network access infrastructure while reducing complexity, improving scalability, and enhancing security. The following types of organizations or environments are especially well-suited to benefit from this model:

1. Enterprises with Distributed or Remote Workforces

Companies with multiple office locations, remote employees, or hybrid work models need centralized control over network access. RADIUS as a Service enables consistent authentication and policy enforcement across all sites and users, without requiring local server deployments.

2. Organizations Moving to the Cloud

Businesses decommissioning on-premises infrastructure in favor of cloud-native services benefit from cloud-based RADIUS. It complements cloud identity providers like Azure AD, Google Workspace, and Okta, allowing seamless authentication without tying access control to legacy data centers.

3. SMBs with Limited IT Resources

Small and mid-sized businesses often lack the resources to deploy and maintain traditional RADIUS servers. A managed RADIUS service provides enterprise-grade authentication capabilities without the overhead, making it easier to enforce strong security practices with minimal administrative burden.

4. Educational Institutions

Schools, colleges, and universities often manage large numbers of students, faculty, and devices connecting to campus Wi-Fi. RADIUS as a Service supports secure access through protocols like 802.1X, and can integrate with student directories and identity systems.

5. Healthcare Providers

Hospitals and clinics require strong access controls to meet compliance requirements like HIPAA. Cloud RADIUS can enforce device- and identity-based access to protect sensitive medical data, while supporting BYOD environments.

6. Retail and Hospitality Chains

Businesses with many branch locations (e.g., retail stores, hotels, franchises) benefit from centralized network access control without the need for on-site infrastructure. Cloud RADIUS ensures secure Wi-Fi access for employees and can also manage segmented guest access.

7. Managed Service Providers (MSPs)

MSPs managing network access for multiple clients can use RADIUS as a Service to offer secure, multi-tenant authentication services. Many platforms include multi-site management, role-based access control, and audit logging tailored for MSP use cases.

8. Organizations Implementing 802.1X and NAC

If you’re deploying 802.1X for wired or wireless access or implementing a Network Access Control (NAC) solution, a cloud RADIUS service can act as the AAA backend. It simplifies enforcement of identity- and posture-based policies without the complexity of managing local servers.

9. Security-Conscious Organizations

Companies subject to compliance frameworks (such as PCI-DSS, HIPAA, or ISO 27001) need strong access controls and audit capabilities. RADIUS as a Service provides centralized visibility, access logging, and secure authentication protocols, helping meet regulatory requirements.

In summary, RADIUS as a Service is suitable for any organization looking to secure network access in a scalable, reliable, and cloud-native way—especially those seeking to simplify IT operations and enhance security posture.