Hi German!

See: GetAdaptersInfo
http://msdn.microsoft.com/library/en-us/iphlp/iphlp/getadaptersinfo.asp

<quote>
Requires Windows XP, Windows 2000 Professional, Windows Me, or Windows 98
</quote>

See: Using the Windows Headers
http://msdn.microsoft.com/library/en-us/winprog/winprog/using_the_windows_headers.asp

In short: you need to define _WIN32_WINNT and WINVER with the correct
values, befor including the h-file.

See also: How To Get the MAC Address for an Ethernet Adapter
http://support.microsoft.com/default.aspx?scid=kb;en-us;118623

Hi German!

The following code works perfectly with VC7.1:

<code>
#include <winsock2.h>
#include <windows.h>
#include <stdio.h>
#include <Iphlpapi.h>
#pragma comment(lib, "Iphlpapi.lib")
#pragma comment(lib, "wsock32.lib")

void main()
{
 ULONG ip;
 ULONG buflen;
 PIP_ADAPTER_INFO pAdInfo = NULL;
 PIP_ADAPTER_INFO pAdInfo_c = NULL;

 buflen = 0;
 GetAdaptersInfo(pAdInfo, &buflen);
 pAdInfo = (struct _IP_ADAPTER_INFO *)new UCHAR[buflen+1];
 pAdInfo_c = pAdInfo;
 if (GetAdaptersInfo(pAdInfo, &buflen) == ERROR_SUCCESS)
 {
  do
  {
   ip = inet_addr(pAdInfo->IpAddressList.IpAddress.String);
   if ((ip != 0)&&(ip != 0x7f000001))
   {
    if (pAdInfo->AddressLength != 0)
    {
      printf("Adapter-Name: %s\nDescription: %s\nAddress:",
pAdInfo->AdapterName, pAdInfo->Description);
      for (int i = 0; i < (int)pAdInfo->AddressLength; i++)
        printf(" %02X", pAdInfo->Address[i]);
      printf("\n\n");
    }
   }
   pAdInfo = pAdInfo->Next;
  } while (pAdInfo != NULL);
 }
 delete pAdInfo_c;
}
</code>

If you use VC6 or older, you need to update your PSDK
(or declare the structure by your own, but then I think you also need to
 dynamically load the address of the funtions; because you do not have
the correct lib-file)

See http://www.voidnish.com/articles/ShowArticle.aspx?code=MacIdChanger 
(comes with full source code)