Testing user HTTP proxy using PHP script - php

Question

Welcome,
I'm writing application what will allow me to try detect what type of HTTP proxy user have installed.
Script calling remote server adding parameter http://xxxx.php?my_ip=real_IP
Here is my application:
<?php
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
$real_ip=$_GET['my_ip'];
$ip1=$_SERVER['HTTP_X_FORWARDED_FOR'];
$ip2=$_SERVER['HTTP_X_FORWARDED'];
$ip3=$_SERVER['HTTP_FORWARDED_FOR'];
$ip4=$_SERVER['HTTP_CLIENT_IP'];
$ip5=$_SERVER['HTTP_VIA'];
$ip6=$_SERVER['REMOTE_ADDR'];
$ip_array[1]=$ip1;
$ip_array[2]=$ip2;
$ip_array[3]=$ip3;
$ip_array[4]=$ip4;
$ip_array[5]=$ip5;
if($ip6==$real_ip)
{
echo "You are not using proxy.";
}
else
{
if(in_array($real_ip, $ip_array))
{
echo "You are using transparent proxy with one releave your ip.";
}
else
{
if( $_SERVER['HTTP_X_FORWARDED_FOR']
|| $_SERVER['HTTP_X_FORWARDED']
|| $_SERVER['HTTP_FORWARDED_FOR']
|| $_SERVER['HTTP_CLIENT_IP']
|| $_SERVER['HTTP_VIA'])
{
echo "You are using anonymous proxy with one protect Your IP but inform www servers about using proxy";
}
else
{
echo "You are using elite proxy, with one hide your IP and don't inform www servers about using proxy";
}
}
}
$table=<<<table
<p>Ip HTTP_X_FORWARDED_FOR FOR : $ip1</p>
<p>Ip HTTP_X_FORWARDED : $ip2</p>
<p>Ip HTTP_FORWARDED_FOR FOR : $ip3</p>
<p>Ip HTTP_CLIENT_IP FOR : $ip4</p>
<p>Ip HTTP_VIA FOR : $ip5</p>
<p>Ip remote addr : $ip6</p>
table;
echo $table;
?>
I run some tests and application looks working very well.
If you have any tips please tell me.
I mean i would like know am i dont miss something important.
Regards

Answer 1

Another way in which some major players (Paypal, eBay, sites that have high security etc) find proxies is by looking up your IP's hostname with gethostbyaddr() which can reveal a source that is likely to be a proxy E.g. server.squid.com (Very obvious example to show you what I mean!)