title: Adding a custom header to ARR requests
body: <p>I'm running a service behind IIS using ARR as a reverse proxy.  I know there are <code>x-forwarded-for</code> and <code>x-arr-log-id</code> headers that are passed along.  However, what I would like is a private key passed in so that the backing application explicitly knows that the request is not local (even though the ARR server is).  I've seen some posts on adding/replacing server variables, but this doesn't seem to come through via the request headers on the backing application.</p>
  
  <p>I'm guessing that there must be some web.config setting that will do this, but have had no luck finding it thus far.</p>
  
  <p>Example: <code>X-PRIVATE-TOKEN: We are the children of Korn!</code></p>
  
  <p>So that I can trust the <code>x-forwarded-for</code> address is the actual address, as opposed to simply distrusting all proxy request's ip address references.</p>