fritzbox_private_dnydns_nginx_proxy_pass_update.php

<?php

$pass = 'yourpassword';
$user = 'yourusername';

// which config file to update
$nginxFile = '/etc/nginx/sites-enabled/mydyndns.domain.com';

$authUser = (isset($_SERVER['PHP_AUTH_USER'])) ? $_SERVER['PHP_AUTH_USER'] : null;
$authPass = (isset($_SERVER['PHP_AUTH_PW'])) ? $_SERVER['PHP_AUTH_PW'] : null;
$ip = (isset($_GET['ip'])) ? $_GET['ip'] : null;


if (($authUser === $user) && ($authPass === $pass) && ($ip)) {
  if ((preg_match('/^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\z/', $ip)) && ($content = file_get_contents($nginxFile))) {
    $content = file_get_contents($nginxFile);
    $content = preg_replace('/([\s\t]*proxy_pass[\s\t]+)(http[s]*:\/\/)(.+?)(\:)/i', '${1}${2}'.$ip.'${4}', $content);
    file_put_contents($nginxFile, $content);
    exit("updated");
  }
}