title: Communication over WAN
body: <p>I want to create app client-server in C# but not only in LAN. There it's easy: TcpListener, TcpClient etc.</p>
  
  <p>I want to make sth like in this e.g.
  On my comp is server that's waiting for a connection.
  Someone in another network has client. He begin connection, but...where...what is a IP of server?
  He see only ip of router.</p>
  
  <p>Any ideas? :)</p>
  
  <p><strong>EDIT</strong></p>
  
  <p>Big problem is also double-NAT</p>