C / C++ / MFC

#include "Iphlpapi.h"
#pragma comment(lib, "iphlpapi.lib")
VOID PrintOperationalEthernet()
{
	BYTE *pBuf=NULL;
	DWORD dwSize=0;
	DWORD dwResult=0;
	BOOL bConnected=FALSE;
	PMIB_IFTABLE pMIBTable;
	CString str;
	GetIfTable(NULL,&dwSize,FALSE);
	pBuf=new BYTE[dwSize];
	pMIBTable=reinterpret_cast<PMIB_IFTABLE>(pBuf);

	if(NO_ERROR == GetIfTable(pMIBTable,&dwSize,FALSE))
	{
		for(UINT i=0; i < pMIBTable->dwNumEntries; ++i)
		{
			if(MIB_IF_TYPE_ETHERNET == pMIBTable->table[i].dwType)
			{
				bConnected = MIB_IF_OPER_STATUS_OPERATIONAL == pMIBTable->table[i].dwOperStatus;
				char szBuf[MAX_PATH];
				sprintf(szBuf,"%s is %s\n",pMIBTable->table[i].bDescr,
					TRUE == bConnected?"Connected":"Offline");
				TRACE(szBuf);
			}
		}
	}
	delete []pBuf;
}

#include <winioctl.h>
typedef ULONG NDIS_OID, *PNDIS_OID;
#define _NDIS_CONTROL_CODE(request,method) CTL_CODE(FILE_DEVICE_PHYSICAL_NETCARD, request, method, FILE_ANY_ACCESS)
#define IOCTL_NDIS_QUERY_GLOBAL_STATS   _NDIS_CONTROL_CODE(0,METHOD_OUT_DIRECT)
#define OID_GEN_MEDIA_CONNECT_STATUS 0x00010114

typedef enum _NDIS_MEDIA_STATE
{ 
	NdisMediaStateConnected,
	NdisMediaStateDisconnected 
} NDIS_MEDIA_STATE,*PNDIS_MEDIA_STATE;

VOID PrintOperationalEthernet()
{
	int index =0;
	DWORD dwType =0;
	HKEY key;
	HKEY cardkey;
	CString str;

	HANDLE hDevice;
	NDIS_OID OidCode = OID_GEN_MEDIA_CONNECT_STATUS;
	ULONG status=0;
	ULONG dwRet=0;
	TCHAR szCardVal[CHAR_MAX];
	TCHAR szDescription[MAX_PATH];
	TCHAR szDevice[MAX_PATH];

	str.Format(_T("SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\NetworkCards\\"));
	if(ERROR_SUCCESS == RegOpenKey(HKEY_LOCAL_MACHINE,str,&key))
	{
		while(ERROR_SUCCESS == RegEnumKey(key,index++,szCardVal,CHAR_MAX))
		{
			str.Format(_T("%s\\%d"),str,_ttoi(szCardVal));
			if(ERROR_SUCCESS == RegOpenKey(HKEY_LOCAL_MACHINE,str,&cardkey))
			{
				str = str.Left(str.ReverseFind('\\'));
				DWORD dwLen = CHAR_MAX * sizeof(TCHAR);
				if(ERROR_SUCCESS == RegQueryValueEx(cardkey,_T("ServiceName"),NULL,
					&dwType,(LPBYTE)szCardVal,&dwLen))
				{
					RegQueryValueEx(cardkey,_T("Description"),NULL,
						&dwType,(LPBYTE)szDescription,&dwLen);
					_stprintf(szDevice,_T("\\\\.\\%s"),szCardVal);
					hDevice = CreateFile(szDevice,GENERIC_READ,FILE_SHARE_READ|
						FILE_SHARE_WRITE,NULL,OPEN_EXISTING,0,0);
					if(DeviceIoControl(hDevice,IOCTL_NDIS_QUERY_GLOBAL_STATS,
						&OidCode,sizeof(NDIS_OID),&status,
						sizeof(ULONG),&dwRet,NULL))
					{
						TCHAR szBuf[MAX_PATH];
						_stprintf(szBuf,_T("%s is %s\n"),szCardVal,
							NdisMediaStateConnected == status?_T("Connected"):_T("Offline"));
						TRACE(szBuf);
						CloseHandle(hDevice);
					}
					RegCloseKey(cardkey);
				}
			}
		}
		RegCloseKey(key);
	}
}

#include <netcon.h>
#define _WIN32_DCOM	1
typedef void(__stdcall *LPNcFreeNetconProperties)(NETCON_PROPERTIES *pProps);
VOID PrintOperationalEthernet()
{
	HRESULT hr = CoInitializeEx(0, COINIT_MULTITHREADED);
	hr = CoInitializeSecurity(NULL, -1, NULL, NULL,
	RPC_C_AUTHN_LEVEL_CONNECT, 
	RPC_C_IMP_LEVEL_IDENTIFY, 
	NULL, EOAC_NONE, 0
	);
	HMODULE hmod=LoadLibrary(_T("netshell.dll"));
	if(hmod)
	{
		LPNcFreeNetconProperties NcFreeNetconProperties=(LPNcFreeNetconProperties)\
			GetProcAddress(hmod,"NcFreeNetconProperties");
		INetConnectionManager *pMan=0;
		HRESULT hres=CoCreateInstance(CLSID_ConnectionManager,0,CLSCTX_ALL,\
			__uuidof(INetConnectionManager),(void **) &pMan);
		if(SUCCEEDED(hres))
		{
			IEnumNetConnection *pEnum=0;
			HRESULT hres=pMan->EnumConnections(NCME_DEFAULT,&pEnum);
			if(SUCCEEDED(hres))
			{
				INetConnection *pCon=0;
				ULONG count;
				bool done=FALSE;
				while(pEnum->Next(1,&pCon,&count) == S_OK && !done)
				{
					NETCON_PROPERTIES *pProps=0;
					hres=pCon->GetProperties(&pProps);
					if(SUCCEEDED(hres))
					{
						wchar_t wszBuf[MAX_PATH];
						wsprintf(wszBuf,_T("%s is %s\n"),pProps->pszwName,
							NCS_CONNECTED == pProps->Status?_T("Connected"):_T("Offline"));
						TRACE(wszBuf);
						NcFreeNetconProperties(pProps);
					}
					pCon->Release();
				}
				pEnum->Release();
			}
		  pMan->Release();
		}
		FreeLibrary(hmod);
	}
	CoUninitialize();
}

Iain Clarke wrote:

If you've just typed all that, I'm impressed!