Exceções da Plataforma de Filtragem do Windows para Teredo

As exceções que permitem que os aplicativos recebam tráfego não solicitado por Teredo por meio de um firewall devem ser criadas usando Plataforma de Filtragem do Windows APIs. Isso é feito abrindo exceções baseadas em aplicativos de entrada e saída (nome do aplicativo <aplicativo>) na subcamada Teredo do ALE para tráfego IPv6. Isso garante que apenas aplicativos com a exceção Teredo possam usar Teredo. Há que ter cuidado na criação destas exceções. O uso da opção geral " * " (todos) pode permitir que programas não registrados na subcamada Teredo ou no tráfego do túnel passem pelo firewall e representem uma ameaça à segurança.

Em qualquer situação, pelo menos um aplicativo bloqueado é necessário, mas pode haver zero ou mais aplicativos permitidos adicionados por um firewall, dependendo de quantos aplicativos precisam ser permitidos.

O exemplo a seguir demonstra o uso de uma autorização e um bloqueio.

/*--
Routine Description:

    Adds the necessary filters to permit specific applications and block all other
    via the Windows Filtering Platform (WFP).

Arguments:
   
   [in] HANDLE engineHandle - Handle to the base firewall engine.
   [in] FWP_BYTE_BLOB* applicationId - Identifier for this application.

Return Value:

    NO_ERROR or a specific Result

--*/
   DWORD Result = NO_ERROR;
   FWPM_FILTER0 Filter;
   FWPM_FILTER_CONDITION0 FilterConditions[3]; // We only need three.
   DWORD TempResult;
   FWP_BYTE_BLOB* applicationId;

   printf("Starting Transaction\n");

   Result = FwpmTransactionBegin0(engineHandle, 0);
   if (NO_ERROR != Result)
   {
      goto abort;
   }
   
   printf("Successfully Started Transaction\n");

   RtlZeroMemory(&Filter, sizeof(FWPM_FILTER0));

   Filter.layerKey = FWPM_LAYER_ALE_AUTH_RECV_ACCEPT_V6;
   Filter.displayData.name = L"Teredo Filter for Application Specific Permit";
   Filter.displayData.description = L"Implement Teredo Filter for Application Specific Permit at the Recv Accept layer";
   Filter.action.type = FWP_ACTION_PERMIT;
   Filter.subLayerKey = FWPM_SUBLAYER_TEREDO;
   Filter.weight.type = FWP_EMPTY; // auto-weight
   Filter.filterCondition = FilterConditions;
   Filter.numFilterConditions = 3;

   RtlZeroMemory(FilterConditions, sizeof(FilterConditions));

   //
   // Enable this for IfType == Tunnel, TunnelType == Teredo.
   //
   FilterConditions[0].fieldKey = FWPM_CONDITION_INTERFACE_TYPE;
   FilterConditions[0].matchType = FWP_MATCH_EQUAL;
   FilterConditions[0].conditionValue.type = FWP_UINT32;
   FilterConditions[0].conditionValue.uint32 = IF_TYPE_TUNNEL;

   //
   // Enable this for IfType == Tunnel, TunnelType == Teredo.
   //
   FilterConditions[1].fieldKey = FWPM_CONDITION_TUNNEL_TYPE;
   FilterConditions[1].matchType = FWP_MATCH_EQUAL;
   FilterConditions[1].conditionValue.type = FWP_UINT32;
   FilterConditions[1].conditionValue.uint32 = TUNNEL_TYPE_TEREDO;

   //
   // Add a permitted application.
   //
   FilterConditions[2].fieldKey = FWPM_CONDITION_ALE_APP_ID;
   FilterConditions[2].matchType = FWP_MATCH_EQUAL;
   FilterConditions[2].conditionValue.type = FWP_BYTE_BLOB_TYPE;
   FilterConditions[2].conditionValue.byteBlob = applicationId;

   printf("Adding Recv Accept Application specific V6 Teredo Filter.\n");

   Result = FwpmFilterAdd0(engineHandle,
                           &Filter,
                           NULL,
                           NULL);

   if (NO_ERROR != Result)
   {
      goto abort;
   }
   
   printf("Successfully added Recv Accept Application specific V6 Teredo Filter.\n");

   Filter.layerKey = FWPM_LAYER_ALE_AUTH_RECV_ACCEPT_V6;
   Filter.displayData.name = L"Teredo Filter for Blocking other applications";
   Filter.displayData.description = L"This blocks any other traffic coming in over the Teredo interface that hasn't explicitly been permitted.";
   Filter.action.type = FWP_ACTION_BLOCK;
   Filter.subLayerKey = FWPM_SUBLAYER_TEREDO;
   Filter.weight.type = FWP_EMPTY; // auto-weight
   Filter.filterCondition = FilterConditions;
   Filter.numFilterConditions = 2;

   RtlZeroMemory(FilterConditions, sizeof(FilterConditions));

   //
   // Enable this for IfType == Tunnel, TunnelType == Teredo.
   //
   FilterConditions[0].fieldKey = FWPM_CONDITION_INTERFACE_TYPE;
   FilterConditions[0].matchType = FWP_MATCH_EQUAL;
   FilterConditions[0].conditionValue.type = FWP_UINT32;
   FilterConditions[0].conditionValue.uint32 = IF_TYPE_TUNNEL;

   //
   // Enable this for IfType == Tunnel, TunnelType == Teredo.
   //
   FilterConditions[1].fieldKey = FWPM_CONDITION_TUNNEL_TYPE;
   FilterConditions[1].matchType = FWP_MATCH_EQUAL;
   FilterConditions[1].conditionValue.type = FWP_UINT32;
   FilterConditions[1].conditionValue.uint32 = TUNNEL_TYPE_TEREDO;

   printf("Adding Recv Accept block all non-permitted V6 Teredo Filter.\n");

   Result = FwpmFilterAdd0(engineHandle,
                           &Filter,
                           NULL,
                           NULL);

   if (NO_ERROR != Result)
   {
      goto abort;
   }
   
   printf("Successfully added Recv Accept block all non-permitted V6 Teredo Filter.\n");

   printf("Committing Transaction\n");
   Result = FwpmTransactionCommit0(engineHandle);
   if (NO_ERROR == Result)
   {
      printf("Successfully Committed Transaction\n");
   }
   goto cleanup;

abort:
   printf("Aborting Transaction\n");
   TempResult = FwpmTransactionAbort0(engineHandle);
   if (NO_ERROR == TempResult)
   {
      printf("Successfully Aborted Transaction\n");
   }

cleanup:
   
   return Result;