title: curl shows no output in tcpdump
body: <p>I'm attempting to diagnose a network issue with <code>tcpdump</code>.  I run the command </p>
  
  <pre><code>tcpdump -i eth0 -nS host nameless.host.io
  </code></pre>
  
  <p>When I issue either <code>traceroute</code> or <code>ping</code> commands to hit <code>nameless.host.io</code> I see information from <code>tcpdump</code> but when I use <code>curl</code> to retrieve content from the host</p>
  
  <pre><code>curl http://nameless.host.io/mycontent/data
  </code></pre>
  
  <p>the <code>curl</code> command returns the content I expect but I see no output from <code>tcpdump</code>.  The host is definitely "external" so it should go out on the wires.  </p>
  
  <p>Why would <code>tcpdump</code> be silent on a successful <code>curl</code> command?</p>