title: Browser IP Address
body: <p>I have 2 apps </p>
  
  <p>1 Ruby (not written by me. I understand nothing of Ruby) and the other ASP.Net</p>
  
  <p>The Ruby app determines the users's IP address (I'm told "using first IP found in "HTTP_X_FORWARDED" )and passes a hashed version of it to the ASP.Net app.</p>
  
  <p>The ASP.Net app then determines the Client's IP address again (using Request.UserHostAddress) and hashes the value. </p>
  
  <p>Then hashes are compared.</p>
  
  <p>Generally these hashes are identical ( as you might expect) for all our clients.</p>
  
  <p>However we have 1 new client for which this is not the case...</p>
  
  <p>Every computer at his workplace apparently produces hashes which are not equal</p>
  
  <p>How can this be?</p>