title: ASP.NET: get external IP address
body: <p>I developed site. I need to get IP of site visitors. 
  I try to use Request, but it have only internal IP:</p>
  
  <pre><code>Response.Write(Request.ServerVariables["REMOTE_ADDR"]);
  </code></pre>
  
  <p>I looked all keys in Server Variables collection - the same result:   </p>
  
  <pre><code>foreach (string var in Request.ServerVariables)
  {
      Response.Write(Request[var]);
  }
  </code></pre>
  
  <p>How can I get external IP address?</p>