crossdomain.xml

<?xml version="1.0"?>
<!DOCTYPE cross-domain-policy SYSTEM "http://www.adobe.com/xml/dtds/cross-domain-policy.dtd">
<cross-domain-policy>

<!-- Read this: www.adobe.com/devnet/articles/crossdomain_policy_file_spec.html -->

<!-- Most restrictive policy: -->
    <site-control permitted-cross-domain-policies="none"/>

<!-- Least restrictive policy: -->
<!--
    <site-control permitted-cross-domain-policies="all"/>
    <allow-access-from domain="*" to-ports="*" secure="false"/>
    <allow-http-request-headers-from domain="*" headers="*" secure="false"/>
-->
<!--
  If you host a crossdomain.xml file with allow-access-from domain="*"
  and don’t understand all of the points described here, you probably
  have a nasty security vulnerability. ~ simon willison
-->

</cross-domain-policy>