Adding a Per Interface Rule

This example adds a per interface rule using the Windows Firewall with Advanced Security APIs.

 
/********************************************************************++
THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF
ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED
TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A
PARTICULAR PURPOSE.

Copyright (C) Microsoft. All Rights Reserved.

Abstract:
    This C++ file includes sample code that adds a rule per interface
    for the currently active profiles using the Microsoft Windows 
    Firewall APIs.

--********************************************************************/

#include <windows.h>
#include <stdio.h>
#include <comdef.h>
#include <netfw.h>


// Forward declarations
HRESULT     WFCOMInitialize(INetFwPolicy2** ppNetFwPolicy2);


int __cdecl main()
{
    HRESULT hrComInit = S_OK;
    HRESULT hr = S_OK;

    variant_t      vtInterfaceName("Local Area Connection"), vtInterface;
    long           index = 0;
    SAFEARRAY      *pSa = NULL;

    INetFwPolicy2 *pNetFwPolicy2 = NULL;
    INetFwRules *pFwRules = NULL;
    INetFwRule *pFwRule = NULL;

    long CurrentProfilesBitMask = 0;

    BSTR bstrRuleName = SysAllocString(L"PER_INTERFACE_RULE");
    BSTR bstrRuleDescription = SysAllocString(L"Add a PER_INTERFACE rule");
    BSTR bstrRuleGroup = SysAllocString(L"Sample Rule Group");
    BSTR bstrRuleLPorts = SysAllocString(L"2300");

    // Initialize COM.
    hrComInit = CoInitializeEx(
                    0,
                    COINIT_APARTMENTTHREADED
                    );

    // Ignore RPC_E_CHANGED_MODE; this just means that COM has already been
    // initialized with a different mode. Since we don't care what the mode is,
    // we'll just use the existing mode.
    if (hrComInit != RPC_E_CHANGED_MODE)
    {
        if (FAILED(hrComInit))
        {
            printf("CoInitializeEx failed: 0x%08lx\n", hrComInit);
            goto Cleanup;
        }
    }

    // Retrieve INetFwPolicy2
    hr = WFCOMInitialize(&amp;pNetFwPolicy2);
    if (FAILED(hr))
    {
        goto Cleanup;
    }

    // Retrieve INetFwRules
    hr = pNetFwPolicy2->get_Rules(&amp;pFwRules);
    if (FAILED(hr))
    {
        printf("get_Rules failed: 0x%08lx\n", hr);
        goto Cleanup;
    }

    // Retrieve Current Profiles bitmask
    hr = pNetFwPolicy2->get_CurrentProfileTypes(&amp;CurrentProfilesBitMask);
    if (FAILED(hr))
    {
        printf("get_CurrentProfileTypes failed: 0x%08lx\n", hr);
        goto Cleanup;
    }

    // When possible we avoid adding firewall rules to the Public profile.
    // If Public is currently active and it is not the only active profile, we remove it from the bitmask
    if ((CurrentProfilesBitMask & NET_FW_PROFILE2_PUBLIC) &amp;&amp;
        (CurrentProfilesBitMask != NET_FW_PROFILE2_PUBLIC))
    {
        CurrentProfilesBitMask ^= NET_FW_PROFILE2_PUBLIC;
    }

    // Retrieve Local Interface
    pSa = SafeArrayCreateVector(VT_VARIANT, 0, 1);
    if (!pSa)
        _com_issue_error(E_OUTOFMEMORY);
    else
    {
        hr = SafeArrayPutElement(pSa, &amp;index, &amp;vtInterfaceName);
        if FAILED(hr)
            _com_issue_error(hr);
        vtInterface.vt = VT_ARRAY | VT_VARIANT;
        vtInterface.parray = pSa;
    }

    // Create a new Firewall Rule object.
    hr = CoCreateInstance(
                __uuidof(NetFwRule),
                NULL,
                CLSCTX_INPROC_SERVER,
                __uuidof(INetFwRule),
                (void**)&amp;pFwRule);
    if (FAILED(hr))
    {
        printf("CoCreateInstance for Firewall Rule failed: 0x%08lx\n", hr);
        goto Cleanup;
    }

    // Populate the Firewall Rule object
    pFwRule->put_Name(bstrRuleName);
    pFwRule->put_Description(bstrRuleDescription);
    pFwRule->put_Enabled(VARIANT_TRUE);
    pFwRule->put_Profiles(CurrentProfilesBitMask);
    pFwRule->put_Grouping(bstrRuleGroup);
    pFwRule->put_Interfaces(vtInterface);
    pFwRule->put_Protocol(NET_FW_IP_PROTOCOL_TCP);
    pFwRule->put_LocalPorts(bstrRuleLPorts);
    pFwRule->put_Action(NET_FW_ACTION_ALLOW);

    // Add the Firewall Rule
    hr = pFwRules->Add(pFwRule);
    if (FAILED(hr))
    {
        printf("Firewall Rule Add failed: 0x%08lx\n", hr);
        goto Cleanup;
    }

Cleanup:

    // Free BSTR's
    SysFreeString(bstrRuleName);
    SysFreeString(bstrRuleDescription);
    SysFreeString(bstrRuleGroup);
    SysFreeString(bstrRuleLPorts);

    // Release the INetFwRule object
    if (pFwRule != NULL)
    {
        pFwRule->Release();
    }

    // Release the INetFwRules object
    if (pFwRules != NULL)
    {
        pFwRules->Release();
    }

    // Release the INetFwPolicy2 object
    if (pNetFwPolicy2 != NULL)
    {
        pNetFwPolicy2->Release();
    }

    // Uninitialize COM.
    if (SUCCEEDED(hrComInit))
    {
        CoUninitialize();
    }
   
    return 0;
}


// Instantiate INetFwPolicy2
HRESULT WFCOMInitialize(INetFwPolicy2** ppNetFwPolicy2)
{
    HRESULT hr = S_OK;

    hr = CoCreateInstance(
        __uuidof(NetFwPolicy2), 
        NULL, 
        CLSCTX_INPROC_SERVER, 
        __uuidof(INetFwPolicy2), 
        (void**)ppNetFwPolicy2);

    if (FAILED(hr))
    {
        printf("CoCreateInstance for INetFwPolicy2 failed: 0x%08lx\n", hr);
        goto Cleanup;        
    }

Cleanup:
    return hr;
}