crossdomain.xml

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

<!-- 
# crossdomain.xml

A cross-domain policy file is an XML document that grants a web client—such as
Adobe Flash Player, Adobe Reader, etc., permission to handle data across
multiple domains. When a client hosts content from a particular source domain
and that content makes requests directed towards a domain other than its own,
the remote domain would need to host a cross-domain policy file that grants
access to the source domain, allowing the client to continue with the
transaction. Policy files grant read access to data, permit a client to include
custom headers in cross-domain requests, and are also used with sockets to
grant permissions for socket-based connections.

For full details, check out Adobe's article about the [cross-domain policy file
specification](http://www.adobe.com/devnet/articles/crossdomain_policy_file_spec.html).
-->