PHP Proxy Detection Function for Web Analytics and User Blocking

Use this PHP function to easily detect if a user is using a proxy, allowing you to implement custom analytics or block them from accessing your website.

function proxy_detected()
{
  if (
     $_SERVER['HTTP_X_FORWARDED_FOR']
  || $_SERVER['HTTP_X_FORWARDED']
  || $_SERVER['HTTP_FORWARDED_FOR']
  || $_SERVER['HTTP_CLIENT_IP']
  || $_SERVER['HTTP_VIA']
  || in_array($_SERVER['REMOTE_PORT'], array(8080,80,6588,8000,3128,553,554))
  || @fsockopen($_SERVER['REMOTE_ADDR'], 80, $errno, $errstr, 1))
  {
      return true;
  } else {
      return false;
  }
}

echo ( proxy_detected() ) ? "Proxy detected" : "No proxy detected";