php ip

getClientIP.php

<?php
if ($_SERVER["HTTP_X_FORWARDED_FOR"]) 
{
    if ($_SERVER["HTTP_CLIENT_IP"]) 
    {
        $proxy = $_SERVER["HTTP_CLIENT_IP"];
    } else {
         $proxy = $_SERVER["REMOTE_ADDR"];
    }
    $ip = $_SERVER["HTTP_X_FORWARDED_FOR"];
    echo $ip . "\n";
} else {
    if ($_SERVER["HTTP_CLIENT_IP"]) 
    {
          $ip = $_SERVER["HTTP_CLIENT_IP"];
    } else {
         $ip = $_SERVER["REMOTE_ADDR"];
    }
}
echo "Your IP $ip";
if (isset($proxy)) 
{
echo "Your proxy IP is $proxy";
}

This is trusting the user agents to not lie to you. ALWAYS capture the REMOTE_ADDR - if you want to save the proxy info also then that's great but don't skip REMOTE_ADDR.