What is COA in NAC - Network Access Control https://www.hacktheforum.com/nac/what-is-coa-in-nac/ Hack The Forum Discussion Board en Wed, 20 May 2026 08:06:15 +0000 wpForo 60 What is COA in NAC https://www.hacktheforum.com/nac/what-is-coa-in-nac/#post-19867 Tue, 29 Jul 2025 02:17:09 +0000 COA (Change of Authorization) is a mechanism defined in the RADIUS protocol (Remote Authentication Dial-In User Service) that allows a RADIUS server (typically a NAC server like Cisco ISE or Aruba ClearPass) to dynamically change a user's network access permissions after they have already been authenticated and connected.

Purpose of COA in NAC

In a NAC environment, COA is used to enforce updated policies without disconnecting the user entirely. For example:

  • A user connects to the network and is granted limited access.

  • Later, the NAC system detects that the user passed security posture assessment or logged in successfully.

  • NAC then sends a COA request to the network device (e.g., switch, wireless controller) to update the session, granting more privileges.

]]> Network Access Control Rinki Singh https://www.hacktheforum.com/nac/what-is-coa-in-nac/#post-19867