linuxexpert-practice-labs/labs/lpic-1/102-6-virtualization-guest/README.md

LPIC-1 102.6: Linux as a virtualization guest

Recognizing a virtual machine from the inside, and fixing what a clone copies from its template.

Before you start

The lab treats this VM as a fresh clone: it notes its machine ID, SSH host keys and hostname as the template's, so task 2 can tell whether you changed them. Reset puts the hostname back, but keeps the new machine ID and host keys. Write answers to the files in /root/lab-answers/.

Tasks

1. Run systemd-detect-virt and lscpu in the VM, and lsmod | grep virtio. Write the hypervisor systemd-detect-virt reports to /root/lab-answers/1.
2. A clone comes out with the same /etc/machine-id, SSH host keys (ssh-keygen -lf /etc/ssh/ssh_host_ed25519_key.pub) and hostname as its template. Fix all three on this VM: a new machine ID, new SSH host keys and a new hostname, all still in place after a reboot, with SSH still working. (ip link would show the same MAC address too; the hypervisor sets that one.)

Hints

• systemd-detect-virt, lscpu | grep -i hypervisor.
• Empty /etc/machine-id (don't delete it), then systemd-machine-id-setup; or systemd-firstboot.
• Remove /etc/ssh/ssh_host_*, then ssh-keygen -A, and restart sshd (ssh on Ubuntu). Your SSH client will warn that the host key changed: remove the old key with ssh-keygen -R.
• hostnamectl set-hostname. On a cloud image, cloud-init sets the hostname again at every boot unless preserve_hostname: true is in a file under /etc/cloud/cloud.cfg.d/.