That won't work (at least not exactly the way you defined it).
You don't have influence on the outgoing port, but you're able to define the incoming one.
For example, your server listens on port 12345 (don't use that port, bad idea) and a client connects. You're then able to use that connection to send and receive.
You can as well have two peer to peer clients, each one opening port 12345 and connecting to that port on the other client. This will work as well.
