4.3 Creating a Demand Dial Interface on RRAS with Filters

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This example illustrates the use of the RPC methods defined in this specification to create a one-way demand-dial interface named "dd1" on the RRAS on Windows Server 2008 operating system. Then, IPv4 filtering is enabled on the demand-dial interface so that the demand-dial is triggered whenever packets with the source address 1.1.1.1 reach the RRAS server.

The client updates the phone book file router.pbk under the file path C:\Windows\System32 to comprise the phonebook entry for dd1, see section 4.10 for details.

The client calls the RPC method RRouterInterfaceCreate (section 3.1.4.13) with the following parameters:

  • The DIM_HANDLE (section 2.2.1.1.6) that the client obtains during initialization (section 3.1.3).

  • The level of information required. In this example, the client specifies level 0.

  • The pointer to DIM_INFORMATION_CONTAINER (section 2.2.1.2.1) (pInfoStruct) that the RRAS server uses to pass the information.

  • The dwBufferSize in the pointer to DIM_INFORMATION_CONTAINER (pInfoStruct) will contain the size of information being passed; in this case, it will be the size of MPRI_INTERFACE_0 (section 2.2.1.2.81).

  • The pBuffer in the pointer to DIM_INFORMATION_CONTAINER (pInfoStruct) will contain a pointer to MPRI_INTERFACE_0.

  • The wszInterfaceName in the pointer to MPRI_INTERFACE_0 is set to L"dd1".

  • The dwIfType in the pointer to MPRI_INTERFACE_0 is set to ROUTER_IF_TYPE_HOME_ROUTER.

When the client calls the RPC method as previously described, it returns ERROR_SUCCESS. Additionally, the following parameter value is updated:

  •  The hInterface specifies a unique identifier of the newly created interface.

The client stores the hInterface returned in MPRI_INTERFACE_0 into a local variable hInterface.

The client frees the buffer pointed to by pBuffer.

The client then calls the RPC method RRouterInterfaceTransportAdd (section 3.1.4.18) to add with the following parameters:

  • The DIM_HANDLE that the client obtains during initialization (section 3.1.3).

  • The pointer to DIM_INTERFACE_CONTAINER (pInfoStruct) that the RRAS server uses to pass the information.

  • The hInterface is the handle to the interface stored locally.

  • The dwTransportId will be set to 0x00000021 since IPv4 filters are being added.

  • The pointer to DIM_INTERFACE_CONTAINER (pInfoStruct) that the RRAS server uses to pass the information.

  • The fGetInterfaceInfo in the pointer to DIM_INTERFACE_CONTAINER (pInfoStruct) is set to 0 because the client is setting information.

  • The dwInterfaceInfoSize in the pointer to DIM_INTERFACE_CONTAINER (pInfoStruct) is set to the size of RTR_INFO_BLOCK_HEADER (section 2.2.1.2.3) with one RTR_TOC_ENTRY (section 2.2.1.2.4) and have the quad memory aligned data for MPR_FILTER_0 0x34.

  • The pInterfaceInfo in the pointer to DIM_INTERFACE_CONTAINER (pInfoStruct) is set to RTR_INFO_BLOCK_HEADER.

  • The Version in RTR_INFO_BLOCK_HEADER is set to 1.

  • The Size is set to 32.

  • The TocEntriesCount is set to 1.

  • The InfoType of RTR_TOC_ENTRY is set to IP_FILTER_ENABLE_INFO (0xFFFF0015).

  • The InfoSize in RTR_TOC_ENTRY is set to 20 (TOC entry 16 byte + 4 bytes mprfilter).

  • The Count in RTR_TOC_ENTRY is set to 1.

  • The Offset is 16 and points to MPR_FILTER_0 (section 2.2.1.2.89).

  • The fEnable in MPR_FILTER_0 is set to 0x00000001 to enable filtering on the RRAS server.

Having enabled filtering on the interface, the client then adds filters on the demand-dial interface. In this example, filtering is enabled on all packets with the source address 1.1.1.1.

The client then calls the RPC method RRouterInterfaceTransportAdd with the following parameters:

  • The DIM_HANDLE that the client obtains during initialization (section 3.1.3).

  • The pointer to DIM_INFORMATION_CONTAINER (pInfoStruct) that the RRAS server uses to pass.

  • The hInterface is the handle to the interface stored locally.

  • The dwTransportId will be set to 0x00000021 for IPv4.

  • The pointer to DIM_INFORMATION_CONTAINER (pInfoStruct) that the RRAS server uses to pass.

  • The fGetInterfaceInfo in the pointer to DIM_INFORMATION_CONTAINER (pInfoStruct) is set to 0 because the client is setting information.

  • The dwInterfaceInfoSize in the pointer to DIM_INFORMATION_CONTAINER (pInfoStruct) is set to 68 (filter descriptor 40 bytes + TOC entry 16 bytes + RTR_INFO_BLOCK_HEADER -Toc 12 bytes).

  • The pInterfaceInfo in the pointer to DIM_INFORMATION_CONTAINER (pInfoStruct) is set to RTR_INFO_BLOCK_HEADER.

  •  The Version in RTR_INFO_BLOCK_HEADER is set to 1.

  • The Size is set to 72 (filter descriptor 40 bytes + TOC entry 32 bytes).

  • The TocEntriesCount is set to 1.

  • The InfoType of RTR_TOC_ENTRY is set to 0xFFFF0009.

  • The InfoSize in RTR_TOC_ENTRY is set to 40 (the size of the filter descriptor).

  • The Count in RTR_TOC_ENTRY is set to 1.

  • The Offset is 32 and points to FILTER_DESCRIPTOR (section 2.2.1.2.5).

  • The dwVersion in FILTER_DESCRIPTOR is set to 0x00000001.

  • The dwNumFilters in FILTER_DESCRIPTOR is set to 0x00000001.

  • The faDefaultAction in FILTER_DESCRIPTOR is set to 0x00000000.

  • The fiFilter contains FILTER_INFO (section 2.2.1.2.6). 

  • The dwSrcAddr in FILTER_INFO is set to 0x01010101 and the rest of the fields in FILTER_INFO are set to 0.