PHP 获取客户端 IP 地址的方法实例代码

先来了解一个变量的含义：

$_SERVER[‘REMOTE_ADDR’]：浏览当前页面的用户计算机的ip地址

$_SERVER[‘HTTP_CLIENT_IP’]：客户端的ip

$_SERVER[‘HTTP_X_FORWARDED_FOR’]：浏览当前页面的用户计算机的网关

$_SERVER[‘HTTP_X_REAL_IP’]：nginx 代理模式下，获取客户端真实IP

/**   * 获取客户端IP地址   */  
function real_ip()  {
    $ip = $_SERVER['REMOTE_ADDR'];
    if (isset($_SERVER['HTTP_X_FORWARDED_FOR']) && preg_match_all('#d{1,3}.d{1,3}.d{1,3}.d{1,3}#s', $_SERVER['HTTP_X_FORWARDED_FOR'], $matches)) {
      foreach ($matches[0] AS $xip) {
        if (!preg_match('#^(10|172.16|192.168).#', $xip)) {
          $ip = $xip;
          break;
        }
      }
    } elseif (isset($_SERVER['HTTP_CLIENT_IP']) && preg_match('/^([0-9]{1,3}.){3}[0-9]{1,3}$/', $_SERVER['HTTP_CLIENT_IP'])) {
      $ip = $_SERVER['HTTP_CLIENT_IP'];
    } elseif (isset($_SERVER['HTTP_CF_CONNECTING_IP']) && preg_match('/^([0-9]{1,3}.){3}[0-9]{1,3}$/', $_SERVER['HTTP_CF_CONNECTING_IP'])) {
      $ip = $_SERVER['HTTP_CF_CONNECTING_IP'];
    } elseif (isset($_SERVER['HTTP_X_REAL_IP']) && preg_match('/^([0-9]{1,3}.){3}[0-9]{1,3}$/', $_SERVER['HTTP_X_REAL_IP'])) {
      $ip = $_SERVER['HTTP_X_REAL_IP'];
    }
    return $ip;
}