title: How to Monitor Sockets activity in a computer?
body: <p>I want to write a program <strong>from scratch</strong> to see the sockets activity, what they send, what they receive, etc. I <strong>don't want to use a Library</strong> because it's more for academic purposes than anything else.</p>
  
  <p>Where should I start?</p>
  
  <p>Just to be clear: my program won't be connecting to anything or creating any socket, it just wants to listen to the activity in a computer.</p>
  
  <p>Any thoughts (in any OS) about where to start will be appreciated.</p>
  
  <p>Thanks in advance.</p>