> because by default firewalls usually block all incoming traffic In Debian by default all connections are allowed. And it makes sense: if you open a port, you

> because by default firewalls usually block all incoming traffic In Debian by default all connections are allowed. And it makes sense: if you open a port, you probably want to be able to connect to it, otherwise why would you open it? It doesn't make sense if you open a port (to accept connections) and then block this port with a firewall. Of course this applies to cases when you have a single node, I understand that you might need firewall if you have several nodes.