This example shows you how to use the NetBIOS API to retrieve the MAC addresses of the network adapters in a system. There are two weaknesses to this approach. The first is that you have to have NetBIOS installed, which implies Windows file/print sharing. The second is that if you have more than one network adapter, you may have to do extra work to figure out which address you really want. If these weaknesses are a problem, you might look at the RPC variation for getting the MAC address.

This code is based on that presented in Microsoft Knowledge Base article KB118623. Of course, my code is cleaner and smarter than theirs is. :)

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getmac-netbios.cpp

// Visual C++ 5.0: cl -GX getmac-netbios.cpp netapi32.lib
// Borland C++ 5.0: bcc32 getmac-netbios.cpp

#include <windows.h>
#include <stdlib.h>
#include <stdio.h>
#include <iostream>
#include <strstream>
#include <string>

using namespace std;

bool GetAdapterInfo(int nAdapterNum, string & sMAC)
{
    // Reset the LAN adapter so that we can begin querying it 
    NCB Ncb;
    memset(&Ncb, 0, sizeof(Ncb));
    Ncb.ncb_command = NCBRESET;
    Ncb.ncb_lana_num = nAdapterNum;
    if (Netbios(&Ncb) != NRC_GOODRET) {
        char acTemp[80];
        ostrstream outs(acTemp, sizeof(acTemp));
        outs << "error " << Ncb.ncb_retcode << " on reset" << ends;
        sMAC = acTemp;
        return false;
    }
    
    // Prepare to get the adapter status block 
    memset(&Ncb, 0, sizeof(Ncb));
    Ncb.ncb_command = NCBASTAT;
    Ncb.ncb_lana_num = nAdapterNum;
    strcpy((char *) Ncb.ncb_callname, "*");
    struct ASTAT {
        ADAPTER_STATUS adapt;
        NAME_BUFFER NameBuff[30];
    } Adapter;
    memset(&Adapter, 0, sizeof(Adapter));
    Ncb.ncb_buffer = (unsigned char *)&Adapter;
    Ncb.ncb_length = sizeof(Adapter);
    
    // Get the adapter's info and, if this works, return it in standard,
    // colon-delimited form.
    if (Netbios(&Ncb) == 0) {
        char acMAC[18];
        sprintf(acMAC, "%02X:%02X:%02X:%02X:%02X:%02X",
                int (Adapter.adapt.adapter_address[0]),
                int (Adapter.adapt.adapter_address[1]),
                int (Adapter.adapt.adapter_address[2]),
                int (Adapter.adapt.adapter_address[3]),
                int (Adapter.adapt.adapter_address[4]),
                int (Adapter.adapt.adapter_address[5]));
        sMAC = acMAC;
        return true;
    }
    else {
        char acTemp[80];
        ostrstream outs(acTemp, sizeof(acTemp));
        outs << "error " << Ncb.ncb_retcode << " on ASTAT" << ends;
        sMAC = acTemp;
        return false;
    }
}

int main()
{
    // Get adapter list
    LANA_ENUM AdapterList;
    NCB Ncb;
    memset(&Ncb, 0, sizeof(NCB));
    Ncb.ncb_command = NCBENUM;
    Ncb.ncb_buffer = (unsigned char *)&AdapterList;
    Ncb.ncb_length = sizeof(AdapterList);
    Netbios(&Ncb);

    // Get all of the local ethernet addresses
    string sMAC;
    for (int i = 0; i < AdapterList.length; ++i) {
        if (GetAdapterInfo(AdapterList.lana[i], sMAC)) {
            cout << "Adapter " << int (AdapterList.lana[i]) <<
                    "'s MAC is " << sMAC << endl;
        }
        else {
            cerr << "Failed to get MAC address! Do you" << endl;
            cerr << "have the NetBIOS protocol installed?" << endl;
            break;
        }
    }

    return 0;
}