PHP获取IP的多种方式解析

<?php
function GetIP(){
if(!empty($_SERVER["HTTP_CLIENT_IP"])){
$cip = $_SERVER["HTTP_CLIENT_IP"];
}else if(!empty($_SERVER["HTTP_X_FORWARDED_FOR"])){
$cip = $_SERVER["HTTP_X_FORWARDED_FOR"];
}else if(!empty($_SERVER["REMOTE_ADDR"])){
$cip = $_SERVER["REMOTE_ADDR"];
}else{
$cip = "无法获取！";
return $cip;
}
}
?>

<?
error_reporting (E_ERROR | E_WARNING | E_PARSE);
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{
$ip = "Unknown";
}
echo "你的IP地址是:".$ip."<br>";
?>

<?
$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;
?>

<?php
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
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;
?>