PHP get real IP (proxy detection)

Question

I do get track the \"real\" IP of an user, if he has an proxy wich sends the header of the real IP... does any of have a better solution, or even more headers?

Sinc

Answer 1

the regex validation would fail for ipv6 addresses; so I would rather remove that (or try to find a better RegEX).

also stripos($proxy_header_temp, ':') would lead to a not expected behaivour for example for "::1" (localhost, ipv6).

my suggestion with mentioned modifications:

function getIp()
{
    $proxy_headers = array(
        'CLIENT_IP',
        'FORWARDED',
        'FORWARDED_FOR',
        'FORWARDED_FOR_IP',
        'HTTP_CLIENT_IP',
        'HTTP_FORWARDED',
        'HTTP_FORWARDED_FOR',
        'HTTP_FORWARDED_FOR_IP',
        'HTTP_PC_REMOTE_ADDR',
        'HTTP_PROXY_CONNECTION',
        'HTTP_VIA',
        'HTTP_X_FORWARDED',
        'HTTP_X_FORWARDED_FOR',
        'HTTP_X_FORWARDED_FOR_IP',
        'HTTP_X_IMFORWARDS',
        'HTTP_XROXY_CONNECTION',
        'VIA',
        'X_FORWARDED',
        'X_FORWARDED_FOR'
    );
    $regEx = "/^([1-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])(\.([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])){3}$/";
    foreach ($proxy_headers as $proxy_header) {
        if (isset($_SERVER[$proxy_header])) {
            /* HEADER ist gesetzt und dies ist eine gültige IP */
            return $_SERVER[$proxy_header];
        } else if (stristr(',', $_SERVER[$proxy_header]) !== false) {
            // Behandle mehrere IPs in einer Anfrage
            //(z.B.: X-Forwarded-For: client1, proxy1, proxy2)
            $proxy_header_temp = trim(
                array_shift(explode(',', $_SERVER[$proxy_header]))
            ); /* Teile in einzelne IPs, gib die letzte zurück und entferne Leerzeichen */

            // if IPv4 address remove port if exists
            if (preg_match($regEx, $proxy_header_temp)
                && ($pos_temp = stripos($proxy_header_temp, ':')) !== false
            ) {
                $proxy_header_temp = substr($proxy_header_temp, 0, $pos_temp);
            }
            return $proxy_header_temp;
        }
    }

    return $_SERVER['REMOTE_ADDR'];
}