Detect your MAC address using NetBIOS in Delphi

program GetMAC; uses Dialogs, SysUtils, nb30; function GetMACAddress(PCName: string) : string; type TASTAT = packed record adapt: nb30.TADAPTERSTATUS; NameBuff: array [0..30] of TNAMEBUFFER; end; var NCB: TNCB; Tmp: String; pASTAT: Pointer; AST: TASTAT; begin // 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. FillChar(NCB, SizeOf(NCB), 0); NCB.ncb_command := Chr(NCBRESET); 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 = "* " FillChar(NCB, SizeOf(NCB), 0); FillChar(NCB.ncb_callname[0], 16, ' '); Move(PCName[1], NCB.ncb_callname[0], Length(PCName)); NCB.ncb_command := Chr(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 := SizeOf(AST); GetMem(pASTAT, NCB.ncb_length); if pASTAT=nil then begin result := 'memory allocation failed!'; exit; end; NCB.ncb_buffer := pASTAT; NetBios(@NCB); Move(NCB.ncb_buffer, AST, SizeOf(AST)); with AST.adapt do Tmp := Format('%.2x-%.2x-%.2x-%.2x-%.2x-%.2x', [ord(adapter_address[0]), ord(adapter_address[1]), ord(adapter_address[2]), ord(adapter_address[3]), ord(adapter_address[4]), ord(adapter_address[5])]); FreeMem(pASTAT); Result := Tmp; end; begin ShowMessage(GetMACAddress('*')); end.

I have tried your method (using NB30) before but it does not always work.
Here is a way that always works:

unit ethernet_address;

interface

uses classes, sysutils;

const
MAX_INTERFACE_NAME_LEN = $100;
ERROR_SUCCESS = 0;
MAXLEN_IFDESCR = $100;
MAXLEN_PHYSADDR = 8;

MIB_IF_OPER_STATUS_NON_OPERATIONAL = 0 ;
MIB_IF_OPER_STATUS_UNREACHABLE = 1;
MIB_IF_OPER_STATUS_DISCONNECTED = 2;
MIB_IF_OPER_STATUS_CONNECTING = 3;
MIB_IF_OPER_STATUS_CONNECTED = 4;
MIB_IF_OPER_STATUS_OPERATIONAL = 5;

MIB_IF_TYPE_OTHER = 1;
MIB_IF_TYPE_ETHERNET = 6;
MIB_IF_TYPE_TOKENRING = 9;
MIB_IF_TYPE_FDDI = 15;
MIB_IF_TYPE_PPP = 23;
MIB_IF_TYPE_LOOPBACK = 24;
MIB_IF_TYPE_SLIP = 28;

MIB_IF_ADMIN_STATUS_UP = 1;
MIB_IF_ADMIN_STATUS_DOWN = 2;
MIB_IF_ADMIN_STATUS_TESTING = 3;

type

MIB_IFROW = Record
wszName : Array[0 .. (MAX_INTERFACE_NAME_LEN*2-1)] of char;
dwIndex : LongInt;
dwType : LongInt;
dwMtu : LongInt;
dwSpeed : LongInt;
dwPhysAddrLen : LongInt;
bPhysAddr : Array[0 .. (MAXLEN_PHYSADDR-1)] of Byte;
dwAdminStatus : LongInt;
dwOperStatus : LongInt;
dwLastChange : LongInt;
dwInOctets : LongInt;
dwInUcastPkts : LongInt;
dwInNUcastPkts : LongInt;
dwInDiscards : LongInt;
dwInErrors : LongInt;
dwInUnknownProtos : LongInt;
dwOutOctets : LongInt;
dwOutUcastPkts : LongInt;
dwOutNUcastPkts : LongInt;
dwOutDiscards : LongInt;
dwOutErrors : LongInt;
dwOutQLen : LongInt;
dwDescrLen : LongInt;
bDescr : Array[0 .. (MAXLEN_IFDESCR - 1)] of Char;
end;

function Get_EthernetAddresses: TStringList;

Function GetIfTable( pIfTable : Pointer;
VAR pdwSize : LongInt;
bOrder : LongInt ): LongInt; stdcall;

implementation

Function GetIfTable; stdcall; external 'IPHLPAPI.DLL';

function Get_EthernetAddresses: TStringList;
const
_MAX_ROWS_ = 20;

type
_IfTable = Record
nRows : LongInt;
ifRow : Array[1.._MAX_ROWS_] of MIB_IFROW;
end;

VAR
pIfTable : ^_IfTable;
TableSize : LongInt;
tmp : String;
i,j : Integer;
ErrCode : LongInt;
begin
pIfTable := nil;
/ /---------------------------------------------------------------
Result:=TStringList.Create;
if Assigned(Result) then
try
//-------------------------------------------------------
// First: just get the buffer size.
// TableSize returns the size needed.
TableSize:=0; // Set to zero so the GetIfTabel function
// won't try to fill the buffer yet,
// but only return the actual size it needs.
GetIfTable(pIfTable, TableSize, 1);
if (TableSize < SizeOf(MIB_IFROW)+Sizeof(LongInt)) then
begin
Exit; // less than 1 table entry?!
end; // if-end.

// Second:
// allocate memory for the buffer and retrieve the
// entire table.
GetMem(pIfTable, TableSize);
ErrCode := GetIfTable(pIfTable, TableSize, 1);
if ErrCode<>ERROR_SUCCESS then
begin
Exit; // OK, that did not work.
// Not enough memory i guess.
end; // if-end.

// Read the ETHERNET addresses.
for i := 1 to pIfTable^.nRows do
try
if pIfTable^.ifRow[i].dwType=MIB_IF_TYPE_ETHERNET then
begin
tmp:='';
for j:=0 to pIfTable^.ifRow[i].dwPhysAddrLen-1 do
begin
tmp := tmp + format('%.2x',
[ pIfTable^.ifRow[i].bPhysAddr[j] ] );
end; // for-end.
//-------------------------------------
if Length(tmp)>0 then Result.Add(tmp);
end; // if-end.
except
Exit;
end; // if-try-except-end.
finally
if Assigned(pIfTable) then FreeMem(pIfTable,TableSize);
end; // if-try-finally-end.
end;

end.
// Enjoy!


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