php获取客户端IP地址的四种方法

<?
$iipp=$_SERVER["REMOTE_ADDR"];
echo $iipp;
?> 

<?php
$user_IP = ($_SERVER["HTTP_VIA"]) ? $_SERVER["HTTP_X_FORWARDED_FOR"] : $_SERVER["REMOTE_ADDR"];
$user_IP = ($user_IP) ? $user_IP : $_SERVER["REMOTE_ADDR"];

echo $user_IP;
?>

<?
function get_real_ip(){
 $ip=false;
 if(!empty($_SERVER["HTTP_CLIENT_IP"])){
  $ip = $_SERVER["HTTP_CLIENT_IP"];
 }
 if (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {
  $ips = explode (", ", $_SERVER['HTTP_X_FORWARDED_FOR']);
  if ($ip) { array_unshift($ips, $ip); $ip = FALSE; }
  for ($i = 0; $i < count($ips); $i++) {
   if (!eregi ("^(10|172\.16|192\.168)\.", $ips[$i])) {
    $ip = $ips[$i];
    break;
   }
  }
 }
 return ($ip ? $ip : $_SERVER['REMOTE_ADDR']);
}

echo get_real_ip();
?> 

<?
//php获取ip的算法
if ($HTTP_SERVER_VARS["HTTP_X_FORWARDED_FOR"])
{
 $ip = $HTTP_SERVER_VARS["HTTP_X_FORWARDED_FOR"];
}
elseif ($HTTP_SERVER_VARS["HTTP_CLIENT_IP"])
{
 $ip = $HTTP_SERVER_VARS["HTTP_CLIENT_IP"];
}
elseif ($HTTP_SERVER_VARS["REMOTE_ADDR"])
{
 $ip = $HTTP_SERVER_VARS["REMOTE_ADDR"];
}
elseif (getenv("HTTP_X_FORWARDED_FOR"))
{
 $ip = getenv("HTTP_X_FORWARDED_FOR");
}
elseif (getenv("HTTP_CLIENT_IP"))
{
 $ip = getenv("HTTP_CLIENT_IP");
}
elseif (getenv("REMOTE_ADDR"))
 {
 $ip = getenv("REMOTE_ADDR");
}
else
{
 $ip = "Unknown";
}
echo "你的IP:".$ip ;
?> 

<?
if(getenv('HTTP_CLIENT_IP')) {
$onlineip = getenv('HTTP_CLIENT_IP');
} elseif(getenv('HTTP_X_FORWARDED_FOR')) {
$onlineip = getenv('HTTP_X_FORWARDED_FOR');
} elseif(getenv('REMOTE_ADDR')) {
$onlineip = getenv('REMOTE_ADDR');
} else {
$onlineip = $HTTP_SERVER_VARS['REMOTE_ADDR'];
}
echo $onlineip;
?>