function sendarp(ipaddr:ulong;temp:dword;ulmacaddr:pointer;ulmacaddrleng:pointer) : Dword; StdCall;

    External 'Iphlpapi.dll' Name 'SendARP';

function GetMACByIP(const Ip:string):string;

var

  MyIp:ulong;

  MyMac:array[0..5] of byte;

  MyMacLength:ulong;

  ErrCode:integer;

begin

  Myip:=inet_addr(PChar(Ip));

  MyMacLength:=Length(MyMac);

  ErrCode:=SendArp(MyIp,0,@MyMac,@MyMacLength);

  if ErrCode = 0 then

     Result := Format('%2.2x:%2.2x:%2.2x:%2.2x:%2.2x:%2.2x',[MyMac[0],MyMac[1],MyMac[2],MyMac[3],MyMac[4],MyMac[5]])

  else

     Result := ''; //EorrCode: ErrCode

end;