function get_client_ip()
{
    foreach (array(
                'HTTP_CLIENT_IP',
                'HTTP_X_FORWARDED_FOR',
                'HTTP_X_FORWARDED',
                'HTTP_X_CLUSTER_CLIENT_IP',
                'HTTP_FORWARDED_FOR',
                'HTTP_FORWARDED',
                'REMOTE_ADDR') as $key) {
        if (array_key_exists($key, $_SERVER)) {
            foreach (explode(',', $_SERVER[$key]) as $ip) {
                $ip = trim($ip);
                if ((bool) filter_var($ip, FILTER_VALIDATE_IP,
                                FILTER_FLAG_IPV4 |
                                FILTER_FLAG_NO_PRIV_RANGE |
                                FILTER_FLAG_NO_RES_RANGE)) {
                    return $ip;
                }
            }
        }
    }
    return null;
}

或压缩版:

function get_ip() {
    foreach (array('HTTP_CLIENT_IP', 'HTTP_X_FORWARDED_FOR', 'HTTP_X_FORWARDED', 'HTTP_X_CLUSTER_CLIENT_IP', 'HTTP_FORWARDED_FOR', 'HTTP_FORWARDED', 'REMOTE_ADDR') as $key) {
        if (array_key_exists($key, $_SERVER) === true) {
            foreach (array_map('trim', explode(',', $_SERVER[$key])) as $ip) {
                if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE) !== false) {
                    return $ip;
                }
            }
        }
    }
}

像下面这样?

if (($ip=filter_input(INPUT_SERVER, 'REMOTE_ADDR', validate_ip)) === false or empty($ip)) {
    exit;
}
echo $ip;

PS

if (($ip=filter_input(INPUT_SERVER, 'REMOTE_ADDR', FILTER_VALIDATE_IP|FILTER_FLAG_NO_PRIV_RANGE|FILTER_FLAG_NO_RES_RANGE)) === false) {
    header('HTTP/1.0 400 Bad Request');
    exit;
}

所有以'HTTP_'或'X-'开头的报头都可能被欺骗，分别由用户定义。如果你想要跟踪，可以使用cookie等。

它应该包含在$_SERVER['REMOTE_ADDR']变量中。

下面的函数确定所有的可能性，并以逗号分隔的格式返回值(ip, ip等)。

它还有一个可选的验证功能(默认禁用的第一个参数)，用于根据(私有范围和保留范围)验证IP地址。

<?php
echo GetClientIP(true);

function GetClientIP($validate = False) {
  $ipkeys = array(
  'REMOTE_ADDR',
  'HTTP_CLIENT_IP',
  'HTTP_X_FORWARDED_FOR',
  'HTTP_X_FORWARDED',
  'HTTP_FORWARDED_FOR',
  'HTTP_FORWARDED',
  'HTTP_X_CLUSTER_CLIENT_IP'
  );

  /*
  Now we check each key against $_SERVER if containing such value
  */
  $ip = array();
  foreach ($ipkeys as $keyword) {
    if (isset($_SERVER[$keyword])) {
      if ($validate) {
        if (ValidatePublicIP($_SERVER[$keyword])) {
          $ip[] = $_SERVER[$keyword];
        }
      }
      else{
        $ip[] = $_SERVER[$keyword];
      }
    }
  }

  $ip = ( empty($ip) ? 'Unknown' : implode(", ", $ip) );
  return $ip;
}

function ValidatePublicIP($ip){
  if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE)) {
    return true;
  }
  else {
    return false;
  }
}

这个函数应该能正常工作

function Get_User_Ip()
{
    $IP = false;
    if (getenv('HTTP_CLIENT_IP'))
    {
        $IP = getenv('HTTP_CLIENT_IP');
    }
    else if(getenv('HTTP_X_FORWARDED_FOR'))
    {
        $IP = getenv('HTTP_X_FORWARDED_FOR');
    }
    else if(getenv('HTTP_X_FORWARDED'))
    {
        $IP = getenv('HTTP_X_FORWARDED');
    }
    else if(getenv('HTTP_FORWARDED_FOR'))
    {
        $IP = getenv('HTTP_FORWARDED_FOR');
    }
    else if(getenv('HTTP_FORWARDED'))
    {
        $IP = getenv('HTTP_FORWARDED');
    }
    else if(getenv('REMOTE_ADDR'))
    {
        $IP = getenv('REMOTE_ADDR');
    }

    //If HTTP_X_FORWARDED_FOR == server ip
    if((($IP) && ($IP == getenv('SERVER_ADDR')) && (getenv('REMOTE_ADDR')) || (!filter_var($IP, FILTER_VALIDATE_IP))))
    {
        $IP = getenv('REMOTE_ADDR');
    }

    if($IP)
    {
        if(!filter_var($IP, FILTER_VALIDATE_IP))
        {
            $IP = false;
        }
    }
    else
    {
        $IP = false;
    }
    return $IP;
}

试试这个:

 $_SERVER['REMOTE_ADDR'];