How Does RADIUS Secure VPN Remote Access

The recent pandemic forced companies globally to reconsider the traditional 9-to-5 grind. New collaborative tools were developed that helped employees work efficiently and communicate effectively from their homes. However, with everyone working away from offices, it also meant that they would be accessing company resources from remote locations. Such a scenario could potentially open the door to many vulnerabilities.


One of the worst-case scenarios enterprises were imagining was their resources being hacked into and abused. A global movement towards better security measures started to avoid such situations, like stronger firewalls and robust VPN systems. The latter had played an essential role in offering remote access to resources even before the pandemic. However, the increase in remote employees required more substantial configurations, such as setting up a robust authentication system like a RADIUS server.


This article dives into how a RADIUS server can make all the difference in securing your VPN and enabling a safe and smooth remote-access experience. It will briefly discuss the workings and different configurations of a VPN system and how a RADIUS server can integrate into it.

Radius and VPN Remote Access

The Ins and Outs Of A Virtual Private Network (VPN)

A Virtual Private Network is one of the most common forms of network security used today. VPN services are available on all levels, from single users to massive corporations and institutions. In simple terms, a VPN is a close-ended network secured by encryption and can only be accessed by specific machines. The IP addresses of these machines are used to authenticate them and allow access to the organization’s private network.


A particular VPN connection employs both hardware and software to provide security functionalities. Each connection has a pair of endpoints that encrypt the data, authenticate the user asking for the data, and encapsulate the information within data structures. With encapsulation, the information transferred is further secured. Endpoints can either be hardware and/or software elements, such as one being a laptop at a remote location and the other being an enterprise’s VPN server.


A VPN uses the internet to transfer data from one machine to another and several techniques to secure this data. The methods include:

  • IP Encapsulation: A traditional TCP/IP network transfers information in chunks called packets. A VPN protects packets by enclosing them with other packets with different IP sources and destination information. By IP encapsulation, the source and destination information of the original packets are secured, and the encapsulating packets use the source and destination addresses of the VPN.
  • Information Payload Encryption: VPNs can entirely, or even partially, encrypt the data part of the packets they are sending. In remote client-to-server communication, as in working remotely, the data part is commonly encrypted and not the headers. In the other case, the source computer that generates the traffic encrypts it, and it gets decrypted in the middle of the journey.
  • Encrypted Authentication: The same encryption system used to secure data packets can authenticate computers that attempt to use the VPN. It is essential because the hosts at the receiving end need to know that the user is approved.


A VPN tries to secure the information sent through it by encrypting it and ensuring its users are approved. In the particular case of encrypted authentication, many enterprises opt for a RADIUS server and try to find out how to set up a RADIUS server.

Integrating a RADIUS Server With A VPN

The Remote Authentication Dial-In User Service (RADIUS) server protocol is a fairly common and robust authentication and authorization system. It is mainly used by large enterprises and institutions that have multiple users constantly having to access IT resources. Once its infrastructure is set up and configured, the protocol authenticates users based on their credentials saved in a database. Most of the work related to its system involves monitoring and maintaining it while the protocol takes care of the rest.


Having a protocol like the RADIUS server integrated with a VPN system makes sure that all users using the VPN system are approved. Afterward, the other security measures enforced by the VPN provide an additional layer of safety. The possibility of integrating RADIUS authentication into your firewall without altering your VPN connection also makes it a significantly viable option. Apart from that, many implementations of RADIUS server like the popular freeRADIUS offer an easy setup with the most commonly used VPN options.

Integrating Radius Server With VPN

The most secure form of integrating a RADIUS server with your VPN uses the EAP-TLS authentication protocol. It employs digital certificates to authenticate users instead of the traditional credential-based system. Such a strategy eliminates the risks that come with having passwords or other forms of credentials.

Other techniques of integrating RADIUS with a VPN involve setting up a NAS client with a RADIUS implementation and putting in all the client information. Afterward, users are added, and an authentication server is configured. Finally, the VPN is configured to use the RADIUS setup and start authenticating and authorizing. While using a RADIUS server for authentication is a good step towards additional network security, it is essential to understand what is RADIUS server and its requirements.

Benefits of Authenticating A VPN With RADIUS Server

There are many advantages of securing the authentication part of a VPN or wireless connection with a RADIUS server protocol. While setting up its infrastructure and integrating it with the primary resources can seem daunting, the benefits greatly justify the efforts.


Some of the main pros of setting up a RADIUS server with a VPN connection are as follows:

  • More Secure: Using the RADIUS server protocol over others like LDAP ensures a more secure authentication for your VPN connection. RADIUS handles authentication and authorization separately. The splitting of responsibilities can quickly achieve two-factor authentication. After connecting to the VPN and accessing the other endpoint, the RADIUS server would be there for additional authentication to access the resources.
  • Allows For Implementing Varying Security Policies: You can also implement different security policies through a RADIUS server. The separation of authentication and authorization allows for user management directly from the directory and not from the authentication server. Additionally, the inclusion of physical hardware components and cryptographic tokens makes it unlikely for a hacker with a user’s password to gain access. 
  • Centralized Monitoring And Configuration: With all operations controlled and configured through a centralized system, RADIUS offers much more control and easier adjustments. The user directory can be easily maintained, and setting the strength of the security is also possible. As most RADIUS implementations claim, it has a set-it-and-forget-it nature.
  • Enjoys Wide Support: The RADIUS protocol is supported by almost all authentication vendors and VPN providers. It has free and open-source options for Windows and Linux, NPS on the former, and freeRadius for the latter. There are also products available from leading networking vendors like Cisco.

Using RADIUS Server To Ensure Secure VPN Access

The pandemic has ushered a new sense of normal in the professional world, where remote work has become possible and even encouraged. More and more enterprises are putting in resources to ensure secure access to resources for remote employees. The adoption of security measures like VPN connections and authentication protocols is only going to increase. In such a climate, it is essential to look into a measure like the RADIUS server for ensuring complete network safety. 

Avatar for Emad Bin Abid
Emad Bin Abid

I'm a software engineer who has a bright vision and a strong interest in designing and engineering software solutions. I readily understand that in today's agile world the development process has to be rapid, reusable, and scalable; hence it is extremely important to develop solutions that are well-designed and embody a well-thought-of architecture as the baseline. Apart from designing and developing business solutions, I'm a content writer who loves to document technical learnings and experiences so that peers in the same industry can also benefit from them.

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