title: Tcpdump - measure for a fixed amount of time
body: <p>Is it possible to specify the time for how long the <code>tcpdump</code> should measure the received and sent packets? 
  I know that the command</p>
  
  <pre><code>tcpdump -c 100
  </code></pre>
  
  <p>specifies that the <code>tcpdump</code> should stop after it received 10 packets. I would like to specify that tcpdump stops after for example 5 minutes</p>