alta 9

firewalld is controlled by /etc/firewalld/zones/public.xml

to install google authenticator
you also have to edit /etc/ssh/sshd_config.d/50-redhat.conf
as it also has “ChallengeResponseAuthentication no” (change to yes)

dnf replaces yum

remove old kernels (more than 2)

dnf remove $(dnf repoquery --installonly --latest-limit=-2 -q)

you’ll want to install net-tools bind-tools qrencode-libs qrencode google-authenticator