gistfile1.php

<?php
function getClientIP() {
    $ip = null;

    //check ip from share internet
    if (!empty($_SERVER['HTTP_CLIENT_IP'])) {
        $ip = $_SERVER['HTTP_CLIENT_IP'];
    }
    //to check ip is pass from proxy
    else if (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {
        // HTTP_X_FORWARDED_FOR might return multiple IPs!
        // The first IP may be the real client behind many proxies,
        // but it can be fake (modified through headers).
        // So what is correct is to get the LAST IP from the list of IPs,
        // which is the IP that connected to your (reverse) proxy
        $xff = $_SERVER['HTTP_X_FORWARDED_FOR'];
        $ip  = (false !== strpos($xff, ',')) ? end(explode(',', $xff)) : $xff;
    }
    else if (!empty($_SERVER['REMOTE_ADDR'])) {
        $ip = $_SERVER['REMOTE_ADDR'];
    }

    return $ip;
}

// CLI safe version:

function getClientIP() {
    $ip = null;

    if (isset($_SERVER)) {
        //check ip from share internet
        if (!empty($_SERVER['HTTP_CLIENT_IP'])) {
            $ip = $_SERVER['HTTP_CLIENT_IP'];
        }
        //to check ip is pass from proxy
        else if (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {
            // HTTP_X_FORWARDED_FOR might return multiple IPs!
            // The first IP may be the real client behind many proxies,
            // but it can be fake (modified through headers).
            // So what is correct is to get the LAST IP from the list of IPs,
            // which is the IP that connected to your (reverse) proxy
            $xff = $_SERVER['HTTP_X_FORWARDED_FOR'];
            $ip  = (false !== strpos($xff, ',')) ? end(explode(',', $xff)) : $xff;
        }
        else if (!empty($_SERVER['REMOTE_ADDR'])) {
            $ip = $_SERVER['REMOTE_ADDR'];
        }
    }
    else {
        //check ip from share internet
        if (getenv('HTTP_CLIENT_IP')) {
            $ip = getenv('HTTP_CLIENT_IP');
        }
        //to check ip is pass from proxy
        else if (getenv('HTTP_X_FORWARDED_FOR')) {
            // HTTP_X_FORWARDED_FOR might return multiple IPs!
            // The first IP may be the real client behind many proxies,
            // but it can be fake (modified through headers).
            // So what is correct is to get the LAST IP from the list of IPs,
            // which is the IP that connected to your (reverse) proxy
            $xff = getenv('HTTP_X_FORWARDED_FOR');
            $ip  = (false !== strpos($xff, ',')) ? end(explode(',', $xff)) : $xff;
        }
        else if (getenv('REMOTE_ADDR')) {
            $ip = getenv('REMOTE_ADDR');
        }
    }

    return $ip;
}