FreePBX cron job script for requesting a list of authorized ip's from a remote server and adding them to a zone

addAuthorizedIPs.php

<?php
/**
 * Script for dynamically adding firewall rules to FreePBX from a remote host.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * @author    Brandon Brown
 * @copyright 2019 Brandon Brown
 * @license   http://opensource.org/licenses/gpl-3.0 GNU General Public License, version 3 (GPLv3)
 */

$data = file_get_contents("https://www.example.com/myAuthorizedIPS");

if(strlen($data) < 7) {
        echo "No possibility of valid IP's found in data\n";
        die();
}

$ipRegex = '\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}';

$existingIPs = shell_exec("/usr/sbin/fwconsole firewall list other");
$ipsInIptables = preg_match_all("/$ipRegex/", $existingIPs, $existingIPsArray);
$ipsToPersist = preg_match_all("/$ipRegex/", $data, $ipsToPersistArray);

$ipTablesSize = sizeof($existingIPsArray);
$ipsToAdd = [];
$ipsToRemove = [];

if($ipTablesSize == 1) {
        $ipsToAdd = array_diff($ipsToPersistArray[0], $existingIPsArray[0]);
        $ipsToRemove = array_diff($existingIPsArray[0], $ipsToPersistArray[0]);
}

if(!empty($ipsToRemove)) {
        $ipsToRemoveList = implode(" ", $ipsToRemove);
        $delCommand = "/usr/sbin/fwconsole firewall del other $ipsToRemoveList";
        system(escapeshellcmd($delCommand));
}

if(!empty($ipsToAdd)) {
        $ipsToAddList = implode(" ", $ipsToAdd);
        $addCommand = "/usr/sbin/fwconsole firewall add other $ipsToAddList";
        system(escapeshellcmd($addCommand));
}


?>