PHP获取客户端IP

有时候我们需要获取客户端的IP去实现一些Web功能，比如天气预报就需要根据访客的IP去算出客户端的地理位置才能显示相应的信息

在PHP中获取客户端的IP非常简单，主要根据$_SERVER['REMOTE_ADDR']或者$_SERVER['REMOTE_HOST']这几个变量获取

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以下代码是一个获取客户端IP的例子

// 琼台博客 www.qttc.net

function getClientIP() {
  $ipaddress = '';
  if (isset($_SERVER['HTTP_CLIENT_IP']))
    $ipaddress = $_SERVER['HTTP_CLIENT_IP'];
  else if(isset($_SERVER['HTTP_X_FORWARDED_FOR']))
    $ipaddress = $_SERVER['HTTP_X_FORWARDED_FOR'];
  else if(isset($_SERVER['HTTP_X_FORWARDED']))
    $ipaddress = $_SERVER['HTTP_X_FORWARDED'];
  else if(isset($_SERVER['HTTP_FORWARDED_FOR']))
    $ipaddress = $_SERVER['HTTP_FORWARDED_FOR'];
  else if(isset($_SERVER['HTTP_FORWARDED']))
    $ipaddress = $_SERVER['HTTP_FORWARDED'];
  else if(isset($_SERVER['REMOTE_ADDR']))
    $ipaddress = $_SERVER['REMOTE_ADDR'];
  else
    $ipaddress = 'UNKNOWN';
  return $ipaddress;
}

使用

// 琼台博客 www.qttc.net

// Get the client IP
$clientIP = getClientIP();

echo $clientIP; // output: 192.168.1.20