The peer, at 10.99.0.2 (name peer), stands in for the other VM. It runs its own sshd and shares this VM's files and users, so its /etc is this VM's /etc. The lab creates user alex (password Lab-Pass-1) and adds a small 64 MiB spare disk, /dev/loop40 (the chapter's vdb), with a filesystem on it. Several files go in /tmp, which Ubuntu empties at boot, so do the tasks without a reboot and run le-lab check before you clean up.

Tasks

Copy /etc/ssh into /tmp/src and mirror /tmp/src/ to /tmp/dst/ with rsync. Add a file /tmp/src/ssh/new.txt and delete /tmp/src/ssh/moduli, try a dry run, then mirror again so that /tmp/dst matches. Finally, copy /tmp/src (no trailing slash) into /tmp/dst2/, and see where it lands.
As alex, set up SSH keys so that alex can log in to the peer ([email protected]) without a password, then pull a copy of the peer's /etc/ into /tmp/other-etc/ with rsync. Files only root can read are skipped with "Permission denied".
Image /dev/loop40 into /tmp/vdb.img with dd and compare the two with cmp. Keep the image until you've run le-lab check.

Hints

rsync -av SRC/ DST/, rsync -avn --delete, rsync -a SRC DST/.
sudo -iu alex, ssh-keygen. The peer shares alex's home directory, so adding the public key to ~/.ssh/authorized_keys is enough (ssh-copy-id needs a password login, which may be turned off). rsync -a [email protected]:/etc/ /tmp/other-etc/.
dd if=DISK of=IMAGE bs=4M status=progress, cmp DISK IMAGE && echo identical.