D-Link DGS-3324SR Product Manual - Page 151

xStack DGS/DXS-3300 Series Layer 3 Stackable Gigabit Ethernet Switch User Manual Understanding 802.1x Port-based and MAC-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 Ethernet Switch RADIUS Server 802.1X Client 802.1X 802.1X 802.1X Client Client Client 802.1X Client 802.1X Client 802.1X Client ... 802.1X Client 802.1X Client Network access controlled port Network access uncontrolled port Figure 6- 100. Example of Typical Port-Based Configuration 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. 136