Configure NPS UDP Port Information

Applies To: Windows Server 2008, Windows Server 2008 R2, Windows Server 2012

Use this procedure to configure User Datagram Protocol (UDP) ports for RADIUS traffic.

You can use the following procedure to configure the ports that Network Policy Server (NPS) uses for RADIUS authentication and accounting traffic.

By default, NPS listens for RADIUS traffic on ports 1812, 1813, 1645, and 1646 for both Internet Protocol version 6 (IPv6) and IPv4 for all installed network adapters.


If you uninstall either IPv4 or IPv6 on a network adapter, NPS does not monitor RADIUS traffic for the uninstalled protocol.

The values of 1812 for authentication and 1813 for accounting are RADIUS standard ports defined in RFCs 2865 and 2866. However, by default, many access servers use ports 1645 for authentication requests and 1646 for accounting requests. No matter which ports you decide to use, make sure that NPS and your access server are configured to use the same ones.


If you do not use the default RADIUS ports, you must configure exceptions on the firewall for the local computer to allow RADIUS traffic on the new ports.

Administrative credentials

To complete this procedure, you must be a member of the Administrators group.

To configure NPS UDP port information

  1. Click Start, click Administrative Tools, and then click Network Policy Server. The NPS console opens.

  2. In the NPS console, right-click Network Policy Server, and then click Properties.

  3. Click the Ports tab, and then prepend the IP address for the network adapter you want to use for RADIUS traffic to the existing port numbers. For example, if you want to use the IP address and RADIUS ports 1812 and 1645 for authentication requests, change the port setting from 1812,1645 to,1645.

    If your RADIUS authentication and RADIUS accounting UDP ports are different from the default values, change the port settings accordingly.

  4. To use multiple port settings for authentication or accounting requests, separate the port numbers with commas.