.. _system-using-port-change-radius-authentication: Changing the Radius Authentication Service Port ================================================= When using a Genian NAC device as a Radius Authentication Server, you can change the port. The service is provided through the known port 1812, and you can change the port with the following process. #. Go to **Preferences** in the top panel. #. Select **RADIUS Server** from the **Service** item on the left. #. Enter **Authentication Port** in the **Authentication Server** settings. #. Click the **Update** button.