linuxexpert-practice-labs/labs/linux-plus/1-6-2-copying-and-imaging/README.md

Linux+ 1.6.2: Copies, syncs and disk images

Mirroring a directory with rsync, pulling files from another machine over SSH, and imaging a disk with dd.

Before you start

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

1. 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.
2. 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".
3. 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.