//注意优先次序

function getRealClientIp($server='') {
	if ($server == '') {
		global $_SERVER;
		$server = &$SERVER;
	}
  if(isset($_SERVER['HTTP_X_REAL_IP'])) {
    $ret = $_SERVER['HTTP_X_REAL_IP'];
  } elseif(isset($_SERVER['HTTP_X_FORWARDED_FOR'])) {
  	$ret = $_SERVER['HTTP_X_FORWARDED_FOR'];
  } else {
    $ret = $_SERVER['REMOTE_ADDR'];
  }
  if (strpos($ret, ',') !== FALSE) {
  	$ips = explode(',', $ret);
  	$ret = trim($ips[0]);
  }
  return $ret;
}