Authenticate OpenVPN Clients Using FreeRADIUS

In today’s digital world, ensuring secure communication is extremely important, especially when remotely accessing sensitive resources. Virtual Private Networks (VPNs) play a crucial role in establishing secure connections over the internet by creating a protected tunnel for transmitting data. OpenVPN, a well-known open-source VPN solution, offers strong encryption and flexibility. However, it is vital to have a reliable authentication mechanism to ensure that only authorized clients can access the VPN. In this post you will learn how you can authenticate OpenVPN clients using freeRADIUS.

What is FreeRADIUS?

FreeRADIUS is a highly popular and reliable open-source server used for authentication, authorization, and accounting (AAA). It functions as a strong framework to handle user authentication and access control in network settings. FreeRADIUS offers support for various authentication methods such as username/password, certificates, token-based authentication, and more. Its versatility and wide range of features make it an excellent option for integrating with OpenVPN to authenticate clients.

What is OpenVPN Authentication?

When it comes to secure and private communication, OpenVPN is widely recognized as one of the most popular solutions for Virtual Private Networks (VPNs). It allows users to establish encrypted tunnels between clients and a central server, ensuring secure data transmission over public networks like the internet. However, it is crucial to authenticate the clients who want to access the OpenVPN server in order to maintain data integrity and confidentiality.

OpenVPN provides several authentication methods, each designed to meet specific security requirements and use cases. Let’s delve into the key aspects of OpenVPN authentication:

Client-Server Communication 

At the heart of OpenVPN’s functionality is its client-server architecture. The server serves as the central point of contact and authority, while clients connect to the server to create a secure tunnel. All data transmitted between the server and clients is encrypted, preventing unauthorized access and eavesdropping.

Robust Client Authentication

Ensuring robust client authentication is crucial in preventing unauthorized access and potential security breaches. Without proper authentication, malicious individuals could gain entry to the VPN and compromise sensitive information. By implementing strong authentication methods, organizations can enforce strict access controls and minimize the risk of unauthorized intrusion.

Installing and Configuring FreeRADIUS:

• Update the System: Make sure your system is up to date by running system updates. This will ensure that you have the latest packages and security patches installed.
• Install FreeRADIUS: Use your package manager, like apt or yum, to install FreeRADIUS on your preferred Linux server distribution. This will handle the installation process for you.

• Basic Configuration: Now, it’s time to configure FreeRADIUS to meet your specific requirements. To do this, you’ll need to modify the main configuration file called radiusd.conf. In this file, you can adjust settings such as log paths, network ports, and database connections according to your needs.
• Database Backend: FreeRADIUS supports various database backends like MySQL, PostgreSQL, and SQLite. You need to choose the one that best fits your requirements and configure the necessary parameters accordingly. This step is crucial for FreeRADIUS to interact with the chosen database system.
• Start FreeRADIUS: Once you have completed the configuration steps, it’s time to enable and start the FreeRADIUS service. Enabling the service ensures that it automatically starts whenever your system boots up. This step is important to ensure the continuous operation of FreeRADIUS.

Integrating FreeRADIUS with OpenVPN:

To integrate FreeRADIUS with OpenVPN, follow these steps:

• Install OpenVPN: Make sure you have OpenVPN installed on your server. You can use the package manager for your chosen Linux distribution to install the OpenVPN package.

Configure OpenVPN Server:

• Open the server.conf file of OpenVPN using a text editor.
• Locate the authentication section and modify the configuration to use FreeRADIUS for client authentication.
• Specify the IP address or hostname of the FreeRADIUS server and the shared secret key used for communication between OpenVPN and FreeRADIUS.

Configuring OpenVPN Server to Authenticate Clients Through FreeRADIUS

Configure Client Certificates:

• Generate client certificates and keys using a tool like Easy-RSA or OpenSSL.
• Set up a Certificate Authority (CA) to sign the client certificates.
• Distribute the client certificates and keys to the appropriate clients.

Adjust Client Configuration:

• Modify the client.conf file of OpenVPN to include the necessary settings for certificate-based authentication.
• Make sure the client configuration matches the server configuration, including the server IP address or hostname and the shared secret key.

Test the Configuration:

• Start the OpenVPN server and verify that it establishes connections successfully with the clients.
• Monitor the FreeRADIUS server logs to observe the authentication process and ensure that clients are authenticated successfully.

Conclusion

In summary, using the FreeRADIUS server to authenticate OpenVPN clients offers a strong and reliable way to manage access to your VPN network. By taking advantage of FreeRADIUS’s reliable authentication system and its seamless integration with OpenVPN, companies can improve their security measures and ensure that only approved clients are able to connect to the VPN. Discover the benefits of our DDOS protected VPS for ultimate online security and performance. You can also read about how you can setup and configuration of FreeRADIUS on Ubuntu 16.