title: Set Host-header when using Python and urllib2
body: <p>I'm using my own resolver and would like to use urllib2 to just connect to the IP (no resolving in urllib2) and I would like set the HTTP Host-header myself. But urllib2 is just ignoring my Host-header:</p>
  
  <pre><code>txheaders = { 'User-Agent': UA, "Host: ": nohttp_url }
  robots = urllib2.Request("http://" + ip  + "/robots.txt", txdata, txheaders)
  </code></pre>