A repository with a wrong URL, serving and using a repository of your own, finding the package that provides a command, and undoing a removal from dnf's history.

Before you start

The lab has added a repository extras-mirror in /etc/yum.repos.d/extras-mirror.repo that points at a wrong URL, so dnf install fails until you deal with it in task 1. It installs createrepo_c, and removes policycoreutils-python-utils if it's installed.

The peer, at 10.99.0.2 (name peer), stands in for the second VM. It shares this VM's files, so download the packages here (the peer has no route to the internet) and serve them from the peer. Get a shell there with sudo ip netns exec lepeer bash.

Tasks

See what the wrong URL of extras-mirror does to dnf install, then disable that repository without deleting its file.
On the peer, serve a copy of a few packages over HTTP: download them with dnf download into /srv/repo, run createrepo_c on the directory, and start python3 -m http.server there, bound to 10.99.0.2. On this VM, configure that repository as lab in /etc/yum.repos.d/lab.repo with signature checking on, and install one of its packages from it with dnf install --repo lab.
Find and install the package that provides the semanage command.
Remove a package you installed, then undo the removal from dnf's history.

Hints

dnf repolist --all; dnf config-manager --set-disabled, or enabled=0.
Pick packages that aren't installed yet, such as tree. In the peer: createrepo_c /srv/repo, then python3 -m http.server 8000 --bind 10.99.0.2 --directory /srv/repo &. The repo file needs baseurl=http://10.99.0.2:8000/, gpgcheck=1 and a gpgkey= from /etc/pki/rpm-gpg/. dnf repoinfo lab; dnf install --repo lab NAME takes it from that repository only.
dnf provides semanage (or '*/semanage'). The first dnf provides downloads the file lists of every repository, which can take several minutes. It isn't hung.
dnf history list, dnf history info, dnf history undo.