简单的php获取IP地址的函数：

/**
获取IP
*/
function GetIp()
{
    if (getenv('HTTP_CLIENT_IP')) {
        $IP = getenv('HTTP_CLIENT_IP');
    }
    elseif (getenv('HTTP_X_FORWARDED_FOR')) {
        $IP = getenv('HTTP_X_FORWARDED_FOR');
    }
    elseif (getenv('HTTP_X_FORWARDED')) {
        $IP = getenv('HTTP_X_FORWARDED');
    }
    elseif (getenv('HTTP_FORWARDED_FOR')) {
        $IP = getenv('HTTP_FORWARDED_FOR');
    }
    elseif (getenv('HTTP_FORWARDED')) {
        $IP = getenv('HTTP_FORWARDED');
    }
    else {
        $IP = $_SERVER['REMOTE_ADDR'];
    }
    if(isset($_GET['debug'])){
      return $_GET['debug'];
    }
    return $IP;
}