title: How to recalculate IP checksum with scapy?
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/5953371/how-to-calculate-a-packet-checksum-without-sending-it">How to calculate a packet checksum without sending it?</a>  </p>
  </blockquote>
  
  
  
  <p>I've spoofed a source IP and MAC address in a captured packet, but now I need to recalculate the checksum so that it checks out once its been received (after being injected into the network of course). I didn't really want to implement the checksum myself, and I was thinking that <code>scapy</code> could do this for me. I read that the <code>show2()</code> function should recalculate the checksum, but I can't seem to get it to work.</p>
  
  <p>So, how can I use <code>scapy</code> to recalculate (and replace) the checksum for a captured + spoofed packet?</p>
  
  <p>Thanks!</p>