I discovered that in contrast to Fedora Iot 34, no firewall is installed on Fedora CoreOS 34.
At least not firewalld/ a firewall controllable with firewall-cmd.
What is the reason for doing so?
And for security reasons, would you advise layering firewalld with rpm-ostree, so it can be used? IMHO a firewall is a good defense in depth mechanism, also (or maybe especially) for servers.
Also if there is a reason it is not installed in CoreOS, why is it in Fedora IoT then?
firewalld requires Python and Fedora CoreOS doesn’t ship Python. We do ship the lower-level iptables/nftables/ebtables tools, but unfortunately we don’t have documentation yet for using them to configure the firewall on FCOS.