Get user's IP address with PHP

user_ip_address.php

<?php

function user_ip_address() {
    if( array_key_exists('HTTP_X_FORWARDED_FOR', $_SERVER) && !empty($_SERVER['HTTP_X_FORWARDED_FOR']) ) {
        if (strpos($_SERVER['HTTP_X_FORWARDED_FOR'], ',')>0) {
            $addr = explode(",",$_SERVER['HTTP_X_FORWARDED_FOR']);
            $ip = filter_var(trim($addr[0]), FILTER_VALIDATE_IP)
            return $ip;
        } else {
            return $_SERVER['HTTP_X_FORWARDED_FOR'];
        }
    } else {
        return $_SERVER['REMOTE_ADDR'];
    }
}

?>

Reference: https://stackoverflow.com/questions/13646690/how-to-get-real-ip-from-visitor