title: HTTP_X_FORWARDED_FOR missing from servervariables in c#
body: <p>I would like to get the ClientIPaddress but when I call to <code>Request.ServerVariables["HTTP_X_FORWARDED_FOR"]</code> I always get <code>NULL</code>. </p>
  
  <p>After checking the list of the <code>Servervariables</code> I noticed that <code>HTTP_X_FORWARDED_FOR</code> is not in the list of options.</p>
  
  <p>Anyone knows how this is possible and how to solve? Or is it normal that this option is not in the list and I'm missing something.</p>
  
  <p>Thanks in advance</p>