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Utilizing the three roles stated above, the 802.1X
protocol provides a stable and secure way of authorizing
and authenticating users attempting to access the
network. Only EAPOL traffic is allowed to pass through
the specified port before a successful authentication is
made. This port is "locked" until the point when a Client
with the correct username and password (and MAC
address if 802.1X is enabled by MAC address) is
granted access and therefore successfully "unlocks" the
port. Once unlocked, normal traffic is allowed to pass
through the port. The following figure displays a more
detailed explanation of how the authentication process
is completed between the three roles stated above.
The D-Link implementation of 802.1X allows network administrators to choose between two types of Access Control
used on the Switch, which are:
1. Port-Based Access Control – This method requires only one user to be authenticated per port by a remote
RADIUS server to allow the remaining users on the same port access to the network.
2. Host-Based Access Control – Using this method, the Switch will automatically learn up to a maximum of 16
MAC addresses by port and set them in a list. Each MAC address must be authenticated by the Switch
using a remote RADIUS server before being allowed access to the Network.
Understanding 802.1X Port-based and Host-based Network Access Control
The original intent behind the development of 802.1X was to leverage the characteristics of point-to-point in LANs. As
any single LAN segment in such infrastructures has no more than two devices attached to it, one of which is a Bridge
Port. The Bridge Port detects events that indicate the attachment of an active device at the remote end of the link, or
an active device becoming inactive. These events can be used to control the authorization state of the Port and initiate
the process of authenticating the attached device if the Port is unauthorized. This is the Port-Based Network Access
Control.
Port-Based Network Access Control
Once the connected device has successfully been
authenticated, the Port then becomes Authorized,
and all subsequent traffic on the Port is not subject to
access control restriction until an event occurs that
causes the Port to become Unauthorized. Hence, if
the Port is actually connected to a shared media LAN
segment with more than one attached device,
successfully authenticating one of the attached
devices effectively provides access to the LAN for all
devices on the shared segment. Clearly, the security
offered in this situation is open to attack.
Host-Based Network Access Control
DES-3810 Series Layer 3 Managed Ethernet Switch Web UI Reference Guide
Figure 9-6 Authentication Process window
Figure 9-7 Port-Based Network Access Control window
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