title: P2P chat by python, with no intermediate server
body: <p>I had found code for peer-to-peer chat, but the thorny problems are :</p>
  
  <p>1- Is there is automatic way for the srver and client to get the IP of each other (often dynamic IP) ?</p>
  
  <p>N.B: I read this questions which use an intermediate server but I can't design my own server, so I am searching for another idea:</p>
  
  <p><a href="https://stackoverflow.com/questions/11576934/creating-peer-to-peer-connections-using-intermediate-server">Creating Peer to Peer connections using intermediate server</a></p>
  
  <p><a href="https://stackoverflow.com/questions/8719581/writing-a-simple-p2p-chat-application?rq=1">Writing a simple P2P chat application</a></p>
  
  <p>2- Can hackers use the port opened by the chat program ?</p>