PHP most accurate / safe way to get real user IP address in 2017

Question

What is the most accurate way to get user\'s IP address in 2017 via PHP?

I\'ve read a lot of SO questions and answers about it, but most of answers are old and comme

Answer 1

How about this one -

public function getClientIP()
    {
        $remoteKeys = [
            'HTTP_X_FORWARDED_FOR',
            'HTTP_CLIENT_IP',
            'HTTP_X_FORWARDED',
            'HTTP_FORWARDED_FOR',
            'HTTP_FORWARDED',
            'REMOTE_ADDR',
            'HTTP_X_CLUSTER_CLIENT_IP',
        ];

        foreach ($remoteKeys as $key) {
            if ($address = getenv($key)) {
                foreach (explode(',', $address) as $ip) {
                    if ($this->isValidIp($ip)) {
                        return $ip;
                    }
                }
            }
        }

        return '127.0.0.0';
    }


    private function isValidIp($ip)
    {
        if (!filter_var($ip, FILTER_VALIDATE_IP,
                FILTER_FLAG_IPV4 | FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE)
            && !filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6 | FILTER_FLAG_NO_PRIV_RANGE)
        ) {
            return false;
        }

        return true;
    }