• When compiling by MingW32, you should give linker option with -lnetapi32

#include <windows.h>
#include <wincon.h>
#include <stdlib.h>
#include <stdio.h>
#include <time.h>

typedef struct _ASTAT_
{
        ADAPTER_STATUS adapt;
        NAME_BUFFER    NameBuff [30];
}ASTAT, * PASTAT;

ASTAT Adapter;

void main (void)
{
        NCB ncb;
        UCHAR uRetCode;
        char NetName[50];

        memset( &ncb, 0, sizeof(ncb) );
        ncb.ncb_command = NCBRESET;
        ncb.ncb_lana_num = 0;

        uRetCode = Netbios( &ncb );
        printf( "The NCBRESET return code is: 0x%x \n", uRetCode );

        memset( &ncb, 0, sizeof(ncb) );
        ncb.ncb_command = NCBASTAT;
        ncb.ncb_lana_num = 0;

        strcpy( ncb.ncb_callname,  "*               " );
        ncb.ncb_buffer = (char *) &Adapter;
        ncb.ncb_length = sizeof(Adapter);

        uRetCode = Netbios( &ncb );
        printf( "The NCBASTAT return code is: 0x%x \n", uRetCode );
        if ( uRetCode == 0 )
        {
                printf( "The Ethernet Number is: %02x%02x%02x%02x%02x%02x\n",
                Adapter.adapt.adapter_address[0],
                Adapter.adapt.adapter_address[1],
                Adapter.adapt.adapter_address[2],
                Adapter.adapt.adapter_address[3],
                Adapter.adapt.adapter_address[4],
                Adapter.adapt.adapter_address[5] );
        }
}

• Also see: Retrieval MAC address in Linux