title: how to set packet size in recvfrom
body: <p>How do I set the packet size when using recvfrom()?</p>
  
  <p>I am trying to capture tcp packets using a Raspberry Pi Model B. I have a python program that uses recvfrom to capture the packets and write them to a .dat file. To be compatible with the matlab code I wrote for post-processing the data. I need size (bytes) of the file to yield an integer value when divided by the packet size (in this case 8568 bytes). Is this possible? If so how do I do this?</p>
  
  <p>Also I am having to shutdown and power back up the tcp source every time I run the code in order to get the recvfrom function to work. I want this to stop, do I need to add a command to clear the port at the beginning or end of the code?</p>
  
  <pre><code> while t &lt; 5:
  time.sleep(1)
  t+=1
  print t
  i=str(t)
  f=open('test_' + i  ,'wb')
  radar=s.recvfrom(8568)
  data=str(radar)
  f.write(data)
  print radar
  if radar == 0:
      print 'no packets'
  if radar != 0:
      print radar
  </code></pre>
  
  <p>f.close()
  s.close()</p>