Only allow specific ips and ip ranges access to xmlrpc.php

xmlrpc.php

<?php

$allow_access = false;
$visitor_ip   = $_SERVER['REMOTE_ADDR'];

// Enter precise ips, or omit the last chunk to do a range
$allowed_ips = array(
    '192.0.118.', // WPCOM Jetpack Range
    '192.0.114.', // WPCOM Jetpack Range
    '192.0.116.', // WPCOM Jetpack Range
    '192.0.101.', // WPCOM Jetpack Range
    '192.0.100.', // WPCOM Jetpack Range
    '192.0.99.',  // WPCOM Jetpack Range
);

// Look through the allowed ips/ranges and determine
// if this visitor should be allowed access
foreach( $allowed_ips as $allowed_ip ) {

        // Is this exact visitor ip allowed access?
        // OR, Is the visitor's ip range allowed access?
        if ( $visitor_ip === $allowed_ip || false !== strpos( $visitor_ip, $allowed_ip ) ) {
                $allow_access = true;
                break;
        }
}

if ( ! $allow_access ) {
        header( 'HTTP/1.0 403 Forbidden' );
        die();
}