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Wireless & Mobility · Advanced

Change of Authorization (CoA)

RADIUS extension (RFC 5176) allowing the server to change or terminate an active session.

Definition

CoA lets a RADIUS server such as Cisco ISE reauthenticate, disconnect, or apply new policy to a client after posture, guest login, or a threat event. The standard port is UDP 3799, though Cisco devices commonly use 1700. It is essential for central web authentication flows.

Exam tip

CoA is sent from the RADIUS server to the network device, the reverse of normal RADIUS.

Related terms