PRADIUS_EXTENSION_PROCESS_2 callback function (authif.h)

Note  Internet Authentication Service (IAS) was renamed Network Policy Server (NPS) starting with Windows Server 2008. The content of this topic applies to both IAS and NPS. Throughout the text, NPS is used to refer to all versions of the service, including the versions originally referred to as IAS.
The RadiusExtensionProcess2 function is an application defined-function and is called by NPS for each authentication or accounting packet that NPS receives from the network access server (NAS). This function is similar to RadiusExtensionProcess. However, RadiusExtensionProcess2 enables an Extension DLL to add, modify, and remove attributes to and from the authentication request or response.


PRADIUS_EXTENSION_PROCESS_2 PradiusExtensionProcess2;

DWORD PradiusExtensionProcess2(


[in, out] pECB

Pointer to a RADIUS_EXTENSION_CONTROL_BLOCK structure. The members of this structure contain values and function pointers that enable the NPS Extension DLL to process the RADIUS packet.

Return value

If the function succeeds, the return value is NO_ERROR.

If the function fails, the return value should be an appropriate error code from WinError.h.


If the return value is anything other than NO_ERROR, NPS discards the request.

The following attributes are read-only. Extension DLLs that implement RadiusExtensionProcess2 cannot add, modify, or remove these attributes within a request or response contained in a RADIUS_EXTENSION_CONTROL_BLOCK.

  • ratCode
  • ratIdentifier
  • ratAuthenticator
  • ratSrcIPAddress
  • ratSrcPort
  • ratProvider
  • ratUniqueId
  • ratSrcIPv6Address
NPS supports multiple Extension DLLs. NPS calls RadiusExtensionProcess2 for each of the DLLs listed in the registry. For more information see Setting Up the Extension DLLs.

NPS Extension DLLs that export RadiusExtensionProcess2 do not need to export RadiusExtensionFreeAttributes.

For more information on the use of this function, see NPS Extensions Process.


Minimum supported client None supported
Minimum supported server Windows Server 2008
Target Platform Windows
Header authif.h

See also

About NPS Extensions

NPS Extensions Functions

NPS Extensions Reference