title: Multiple processes listening on the same port?
body: <p>I am trying to understand how can it be possible to start multiple processes listening on the same TCP {IP, Port} pair on Windows XP.</p>
  
  <p>For example, I can start two <code>ncat.exe</code> programs listening on port 371. The second one is started without any problem and receives incoming connections while the first one does not. Once the process lastly started is terminated, the first one receives them.</p>
  
  <pre><code>netstat -a -n | find "LISTENING"
     TCP    0.0.0.0:371            0.0.0.0:0              LISTENING
     TCP    0.0.0.0:371            0.0.0.0:0              LISTENING
  </code></pre>
  
  <p>Assuming this a Windows (XP) behaviour, how can it be a safe &amp; secure behaviour? It means one can "overload" any already listening port instead of getting the usual "address already in use" error message, and simply bypass firewalls with rules just saying "any incoming TCP connections on port 371 are allowed".</p>