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Understanding 802.1X
The original intent behind the development of 802.1X was to leverage the characteristics of
Port-Based Network Access Control
Ethernet Switch
RADIUS
Server
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802.1X | 802.1X | 802.1X | 802.1X | 802.1X | 802.1X | 802.1X | 802.1X | 802.1X |
Client | Client | Client | Client | Client | Client | Client | Client | Client |
Network access controlled port
Network access uncontrolled port
Figure 10- 10. 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.
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