Part 6: Security layer

27. Save a snapshot first#

What you'll do: copy the current settings into a private folder, so you can put them back if a change goes wrong. Time: 5 minutes.

Step 1: Make the snapshot#

snap="/root/snapshot-$(date +%Y%m%d-%H%M)"
sudo install -d -m 700 "$snap"
sudo tar -czf "$snap/config.tar.gz" -C / etc/ssh etc/ufw etc/apt/apt.conf.d etc/systemd/system
sudo chmod 600 "$snap/config.tar.gz"
echo "Saved in $snap"

Write the folder name it prints in your notebook.

Step 2: Write down how things are now#

sudo ufw status numbered
sudo ss -lntup
systemctl --failed

Keep this output. Copy it into a note on your computer. Later you can compare "before" and "after".

ss -lntup lists every program waiting for connections:

How to undo (only if needed)#

To put one file back from the snapshot, e.g. the SSH settings:

sudo tar -xzf /root/snapshot-YYYYMMDD-HHMM/config.tar.gz -C / etc/ssh
sudo systemctl reload ssh

Use your real folder name.

Next: 28. Tighten SSH