title: Get all the layers in a packet
body: <p>How can I get a list of all the layers in scapy?
  Eg: <code>Ether/IP/UDP/DNS</code> or <code>Ether/IP/TCP/HTTP</code>.
  The only thing I can think of is to do a <code>packet.summary()</code> and parse the output, which seems very crude. I think there should be a method built-in, but cannot find any in the documentation. Any suggestions?</p>
  
  <p>What I am trying to do is to iterate over all the fields of a specific protocol given by a user and display its values.</p>
  
  <p>Update:
  What I am looking for exactly can be seen in wireshark: Open any capture, select a packet, and in the 'Frame' menu, one can see
  <code>Protocols in frame: eth:ip:udp:data</code>
  This is exactly what I am looking for in Scapy. I hope I am clearer now.</p>