Get the real IP address of the client and optionally also the one from the proxy server.

am_get_real_ip.php

<?php

/**
 * Get the IP address of the client.
 *
 * @author Arno Moonen <info@arnom.nl>
 * @version 0.1-201112231035
 * @param boolean $get_all Set to true to get an array containing all the IP addresses found.
 * @return mixed Depending on the value of $get_all the return value will be either a string or an array
 */
function am_get_real_ip($get_all = false)
{

    $keys = array(
        "HTTP_CLIENT_IP",
        "HTTP_X_FORWARDED_FOR",
        "HTTP_X_FORWARDED",
        "HTTP_FORWARDED_FOR",
        "HTTP_FORWARDED",
        "REMOTE_ADDR",
    );

    $ips = array();

    foreach ($keys as $X) {
        if (array_key_exists($X, $_SERVER) && !empty($_SERVER[$X])) {

            if (!$get_all) {
                return $_SERVER[$X];
            }

            $ips[$X] = $_SERVER[$X];
        }
    }

    return array_unique($ips, SORT_STRING);
}