802.1X Authentication: A Port-based Network Access Control Protocol

Posted on Jan 26, 2024 by

The Background of 802.1X Protocol

In the early IEEE 802 LAN protocols, users can access devices or resources in a LAN as long as they can access the control device (for example, an access switch ) in the LAN. This obviously brings security risks. To resolve security issues on wireless LANs (WLANs), the IEEE 802 committee proposed the 802.1X protocol to control the network access rights of users. This protocol effectively prevents unauthorized users from transmitting and receiving data. Due to its good universality, 802.1X has also been widely used on wired LANs.

802.1X Authentication Definition

802.1X authentication is a network access control standard that provides a framework for securing and controlling access to a local area network (LAN) or a wireless LAN (WLAN). It is defined in the IEEE 802.1X standard and is widely used to ensure that only authorized devices and users can connect to a network. In 802.1X protocol , the authentication process involves three main entities:

  • Supplicant: The device (such as a computer or smartphone) that is attempting to connect to the network.

  • Authenticator: The network device (such as a switch or Wi-Fi access point) that controls physical access to the network.

  • Authentication Server: A server that verifies the credentials provided by the supplicant. This server is often a RADIUS (Remote Authentication Dial-In User Service) server.

The IEEE 802.1X Working Group endeavors to improve 802.1X authentication, as well as other technologies that impact 802 architecture. This article will discuss 802.1 authentication step by step, as well as how it can be used.


How Does 802.1X Authentication Work?

802.1X authentication works through a series of steps involving the supplicant (device trying to connect), authenticator (network device controlling access), and authentication server. Here's a detailed explanation of the process:

  • Initiation:Initially, the port on the network device (authenticator) is in a "closed" or unauthorized state.The supplicant (device) initiates the authentication process by sending an EAP (Extensible Authentication Protocol) start message to the authenticator.

  • Authentication:Once there is agreement between the supplicant and the authentication server in the initiation phase, EAP responses and requests get transferred between the authentication server and the supplicant, and the authentication server replies with either a success or failure message. If the authentication process succeeds, the authenticator then designates the port as “authorized.” This state enables normal traffic to pass through. If the process does not succeed, the port maintains a state of being “unauthorized.” This results in all non-EAP traffic getting blocked.

  • Authorization:Once the user enrolls for a public key infrastructure certificate or confirms the validity of their credentials, they are authorized to access the network. RADIUS checks to make sure they have the right certificate or the necessary credentials every time they connect. This helps prevent illegitimate users from getting on the network.

What Can You Do with 802.1X Authentication?

802.1X authentication provides a robust framework for controlling access to a network, offering several benefits and capabilities. Here are some of the things you can achieve with 802.1X authentication:

Enhanced Network Security

802.1X helps in preventing unauthorized devices from gaining access to the network. Only devices with valid credentials are allowed to connect, enhancing overall network security.

User Authentication

Users or devices connecting to the network need to provide valid credentials (such as usernames and passwords) for authentication. This ensures that only authorized users can access network resources.

Device Authentication

Beyond user authentication, 802.1X can be used to authenticate devices based on their unique identifiers, such as MAC addresses or digital certificates. This is particularly useful for IoT (Internet of Things) devices.

Centralized Authentication

802.1X allows for centralized authentication through an authentication server (often a RADIUS server). This centralization simplifies user management and ensures consistent authentication policies across the network.

Dynamic VLAN Assignment

Based on the authentication result, 802.1X can dynamically assign devices to specific VLANs. This enables network segmentation and enhances security by isolating devices into appropriate network segments.



In conclusion, 802.1X authentication is a powerful tool for securing network access, enforcing policies, and ensuring that only authorized entities connect to the network. Do you want to know more about us? FS offers a range of solutions for your business. Book a demo or sign up for a free trial.

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