SAML 2 (Ping Federate) Should the AssertionConsumerServiceURL be accessible by the IdP?
<p>We are building a website using SSO, we are on the SP side and don't have control over the IdP. We will have multiple environment including local  development servers.</p>

<p>The thing is the AssertionConsumerServiceURL will not be accessible by the outside world (it would be something like 127.0.0.1/xyz) and I was told that it was a problem because the IdP needed to make a POST request to that server. </p>

<p>However for what I understood of the <a href="https://en.wikipedia.org/wiki/SAML_2.0#SP_POST_Request.3B_IdP_POST_Response" rel="nofollow">"double post" method</a>, only the user needs to be able to access the SP and there is no direct communication between the SP and IdP (since the user is the relay).</p>

<p>Could you please indicate if the IdP needs to access the SP "AssertionConsumerServiceURL" directly ? 
If so, how should local development environment be handled ?</p>