Why is iptables empty and not all ports in netstat?

Question

linux

iptables -L shows that everything is allowed
netstat -ntulp shows only a set of ports, some with LISTEN status, others with empty status
Why so?
Does this mean that I can hang the application on any port and it will work?

Answer 1

You yourself write that everything is allowed. This means that by raising a new service to the desired port, the port will be open and you will see it in netstat LISTEN.