code: public static function getCurrentMacAddress($interface)
      {
          $ifconfig = self::runCommand("ifconfig {$interface}");
          preg_match("/" . self::$valid_mac . "/i", $ifconfig, $ifconfig);
          if (isset($ifconfig[0])) {
              return trim(strtoupper($ifconfig[0]));
          }
          return false;
      }
docs: Get the system's current MAC address
  @param string $interface The name of the interface e.g. eth0
  @return string|bool Systems current MAC address; otherwise false on error