diff --git a/sdk/include/reactos/netcfgn_undoc.h b/sdk/include/reactos/netcfgn_undoc.h
index 0e104bd504f..5923dd2740e 100644
--- a/sdk/include/reactos/netcfgn_undoc.h
+++ b/sdk/include/reactos/netcfgn_undoc.h
@@ -1,6 +1,14 @@
 #ifndef __NETCFGN_UNDOC_H__
 #define __NETCFGN_UNDOC_H__
 
+typedef struct _TCPIP_PROPERTIES
+{
+    DWORD dwDhcp;
+    PWSTR pszIpAddress;
+    PWSTR pszSubnetMask;
+    PWSTR pszParameters;
+} TCPIP_PROPERTIES, *PTCPIP_PROPERTIES;
+
 #undef  INTERFACE
 #define INTERFACE ITcpipProperties
 DECLARE_INTERFACE_(ITcpipProperties, IUnknown)
@@ -8,7 +16,7 @@ DECLARE_INTERFACE_(ITcpipProperties, IUnknown)
     STDMETHOD_(HRESULT,QueryInterface)(THIS_ REFIID riid, void **ppv) PURE;
     STDMETHOD_(ULONG,AddRef)(THIS)  PURE;
     STDMETHOD_(ULONG,Release) (THIS) PURE;
-    STDMETHOD_(HRESULT,Unknown1)(THIS_ DWORD dwParam1, DWORD dwParam2) PURE;
+    STDMETHOD_(HRESULT,Unknown1)(THIS_ GUID *pAdapterName, PTCPIP_PROPERTIES *ppProperties) PURE;
     /* ??? */
 };
 #undef INTERFACE