D-Link DES-3528 Product Manual - Page 213

xStack® DES-3528/DES-3552 Series Layer 2 Stackable Fast Ethernet Managed Switch Web UI Reference Guide Authentication Process 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. Figure 8-6 The 802.1X Authentication Process 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 448 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. Ethernet Switch RADIUS Server 802.1X Client 802.1X 802.1X Client Client 802.1X 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 8-7 Example of Typical Port-based Configuration 204