Question

I have two applications. One is the server app and the other is the client app. The server app listens for connections and then feeds messages to all connected clients.

So far all my testing has been done by running both applications on the same machine, and this is working fine. Now though I am trying to test the server running on one machine and the client running on a different machine.

Each of these machines are within my own home network. That network is behind a router with a firewall. From what I have read, my problem might have to do with port forwarding not setup on my router. Does that sound likely?

Is this something I can fix with just my code? Do I really have to require all my users to manually open the port on their firewalls? I have used plenty of other commercial applications that connect to servers and don’t require me to open ports on my firewall. What is different about those applications and mine?

Then again, maybe I am barking up the wrong tree here. Maybe there is some other problem preventing my code from working in this situation?

I can provide any code snippets that might help, but I am unsure as to where to start looking and I don’t want to just post my entire solution 🙂

Thank you in advance

Answer 1

You need to bind to 0.0.0.0 (simplified version) in order to accept connections not coming from the local machine. Have you checked that you don’t bind to 127.0.0.1?

When you bind to 0.0.0.0 you actually bind to all current and future addresses of the current host and so will be able to accept connections from everywhere, you can also bind to just the address of one of the network interfaces.