Función y declaraciones API para averiguar la MAC ADDRESS de un equipo
o cómo averiguar la dirección de la tarjeta de red

Fecha: 08/Oct/2001 (06/Oct/2001)
Autor: Giovanni Notarnicola < giovanninotarnicola@hotmail.com >

Pôs lo dicho, aquí lo llevas, el código no es mío ni me acuerdo de dónde lo saqué...

Un saludo

Nota del Guille:
Para aclarar conceptos, esto devuelve la dirección de la tarjeta de red.
MAC es: Media Access Control
 

Public Const NCBASTAT As Long = &H33
Public Const NCBNAMSZ As Long = 16
Public Const HEAP_ZERO_MEMORY As Long = &H8
Public Const HEAP_GENERATE_EXCEPTIONS As Long = &H4
Public Const NCBRESET As Long = &H32

Public Type NET_CONTROL_BLOCK  'NCB
   ncb_command    As Byte
   ncb_retcode    As Byte
   ncb_lsn        As Byte
   ncb_num        As Byte
   ncb_buffer     As Long
   ncb_length     As Integer
   ncb_callname   As String * NCBNAMSZ
   ncb_name       As String * NCBNAMSZ
   ncb_rto        As Byte
   ncb_sto        As Byte
   ncb_post       As Long
   ncb_lana_num   As Byte
   ncb_cmd_cplt   As Byte
   ncb_reserve(9) As Byte ' Reserved, must be 0
   ncb_event      As Long
End Type

Public Type ADAPTER_STATUS
   adapter_address(5) As Byte
   rev_major         As Byte
   reserved0         As Byte
   adapter_type      As Byte
   rev_minor         As Byte
   duration          As Integer
   frmr_recv         As Integer
   frmr_xmit         As Integer
   iframe_recv_err   As Integer
   xmit_aborts       As Integer
   xmit_success      As Long
   recv_success      As Long
   iframe_xmit_err   As Integer
   recv_buff_unavail As Integer
   t1_timeouts       As Integer
   ti_timeouts       As Integer
   Reserved1         As Long
   free_ncbs         As Integer
   max_cfg_ncbs      As Integer
   max_ncbs          As Integer
   xmit_buf_unavail  As Integer
   max_dgram_size    As Integer
   pending_sess      As Integer
   max_cfg_sess      As Integer
   max_sess          As Integer
   max_sess_pkt_size As Integer
   name_count        As Integer
End Type

Public Type NAME_BUFFER
   name        As String * NCBNAMSZ
   name_num    As Integer
   name_flags  As Integer
End Type

Public Type ASTAT
   adapt          As ADAPTER_STATUS
   NameBuff(30)   As NAME_BUFFER
End Type

Public Declare Function Netbios Lib "netapi32.dll" _
   (pncb As NET_CONTROL_BLOCK) As Byte

Public Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" _
   (hpvDest As Any, ByVal _
    hpvSource As Long, ByVal _
    cbCopy As Long)

Public Declare Function GetProcessHeap Lib "kernel32" () As Long

Public Declare Function HeapAlloc Lib "kernel32" _
    (ByVal hHeap As Long, ByVal dwFlags As Long, _
     ByVal dwBytes As Long) As Long

Public Declare Function HeapFree Lib "kernel32" _
    (ByVal hHeap As Long, _
     ByVal dwFlags As Long, _
     lpMem As Any) As Long


Public Function GetMACAddress() As String
    'Devuelve la dirección MAC del dispositivo de red
    'instalado, devuelve una cadena formateada

     Dim Tmp As String, pASTAT As Long
     Dim NCB As NET_CONTROL_BLOCK, AST As ASTAT

    'The IBM NetBIOS 3.0 specifications defines four basic
    'NetBIOS environments under the NCBRESET command. Win32
    'follows the OS/2 Dynamic Link Routine (DLR) environment.
    'This means that the first NCB issued by an application
    'must be a NCBRESET, with the exception of NCBENUM.
    'The Windows NT implementation differs from the IBM
    'NetBIOS 3.0 specifications in the NCB_CALLNAME field.
     NCB.ncb_command = NCBRESET
     Call Netbios(NCB)

    'To get the Media Access Control (MAC) address for an
    'ethernet adapter programmatically, use the Netbios()
    'NCBASTAT command and provide a "*" as the name in the
    'NCB.ncb_CallName field (in a 16-chr string).
     NCB.ncb_callname = "*               "
     NCB.ncb_command = NCBASTAT

    'For machines with multiple network adapters you need to
    'enumerate the LANA numbers and perform the NCBASTAT
    'command on each. Even when you have a single network
    'adapter, it is a good idea to enumerate valid LANA numbers
    'first and perform the NCBASTAT on one of the valid LANA
    'numbers. It is considered bad programming to hardcode the
    'LANA number to 0 (see the comments section below).
     NCB.ncb_lana_num = 0
     NCB.ncb_length = Len(AST)

     pASTAT = HeapAlloc(GetProcessHeap(), HEAP_GENERATE_EXCEPTIONS _
              Or HEAP_ZERO_MEMORY, NCB.ncb_length)

     If pASTAT = 0 Then
        Debug.Print "memory allocation failed!"
        Exit Function
     End If

     NCB.ncb_buffer = pASTAT
     Call Netbios(NCB)

     CopyMemory AST, NCB.ncb_buffer, Len(AST)

     Tmp = Format$(Hex(AST.adapt.adapter_address(0)), "00") & "-" & _
           Format$(Hex(AST.adapt.adapter_address(1)), "00") & "-" & _
           Format$(Hex(AST.adapt.adapter_address(2)), "00") & "-" & _
           Format$(Hex(AST.adapt.adapter_address(3)), "00") & "-" & _
           Format$(Hex(AST.adapt.adapter_address(4)), "00") & "-" & _
           Format$(Hex(AST.adapt.adapter_address(5)), "00")

     HeapFree GetProcessHeap(), 0, pASTAT

     GetMACAddress = Tmp
End Function