sub getMacForIP {
   my $ip = shift;
   my $if = shift;
   my $struc = "SCCCCCCCCCCCCCCSCCCCCCCCCCCCCCiSCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC";

   my @x = split("", 0 x 62);
   $x[0] = $main::AF_INET;
   my $i = 0;
   foreach my $c (split(//, $if)) {
      $x[46+$i++] = ord($c)
   }
   $i = 0;
   foreach my $c (split(/\./, $ip)) {
      $x[3+$i++] = $c
   }
   my $arpreq = pack($struc, @x);
   return 0 unless (ioctl(SOCKET,$main::SIOCGARP,$arpreq));
   return join("", map { length($_) > 1 ? $_ : "0".$_ } map { sprintf("%X", $_) } ((unpack($struc, $arpreq))[16..21]));
}