Convert a UA provided IPv4-address to it's hexadecimal value

ip4_to_hex.php

<?php
function ip4_to_hex($ip_address = null) {
	if ($ip_address === null || filter_var($ip_address, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4) === false) return 'Unable to read IP address';
	$fragments = explode('.', $ip_address);
	return sprintf('%02x%02x%02x%02x', $fragments[0], $fragments[1], $fragments[2], $fragments[3]);
}

print ip4_to_hex($_SERVER['REMOTE_ADDR']);