Yeah this. If port forwarding isn't configured on the router, the router won't even know what machine to forward incoming connections to on your network. Furthermore, most Linux distros will not run publicly accessible services unless you install them and start them with systemd/init. Even still, many of these services require a tweak in configuration to accept connections from public IP addresses.
If you have a router then you're fine.
Yeah this. If port forwarding isn't configured on the router, the router won't even know what machine to forward incoming connections to on your network. Furthermore, most Linux distros will not run publicly accessible services unless you install them and start them with systemd/init. Even still, many of these services require a tweak in configuration to accept connections from public IP addresses.