This is an original planning guide. It is not a vendor manual, an official standard, or legal advice. Example addresses use documentation ranges. Review every command before you paste it.
What this hour is for
Sandboxing limits what a service may touch: a private temporary directory, no new privileges, or a path it may write. The hardening generator drafts unit settings. It does not reload systemd and it does not edit a unit under /usr.
One setting. Apply it later on a lab host, with a console open, because a bad setting stops the service. Do not set ProtectSystem or a path limit you cannot explain. The service user is still not root unless the ticket says why.
If the service fails, the journal is the next page. Do not remove every sandbox line at once to make it start. 192.0.2.10/24 and example.com are documentation. They stay in the note.
The change you can finish
Apply nothing while you are writing the note. When the lab window opens, it is one change on the host named in the ticket. Read the draft, then the host, then decide.
Rollback is the file, the package version, or the snapshot you saved first. You do not invent a rollback after the only copy is gone.
- Name the unit and the one limit.
- Draft the drop-in.
- Read what the service can no longer do.
- Keep a console path written down.
- Do not daemon-reload during the reading.
- Stop.
Mistakes that outlive the command
systemd Service Sandboxing Explained goes wrong in a small set of ways. The list is here so the ticket can forbid them before the window.
- Every sandbox option turned on at once.
- A unit edited under /usr.
- The admin session sandboxed by mistake.
- A reload during the reading.
- All limits removed because the service failed once.
Decisions to write down
One decision for systemd Service Sandboxing Explained: One setting. The unit is yours. The console path is known. Nothing was reloaded yet. And the service user is named.
Checks before you call it done
Confirm this before you call the change done: The unit is written. The one setting is written. No reload was done. The path is not under /usr. And a failure would be read, not hidden. If one of those fails, stop.
# One sandbox setting.
# Do not edit /usr.
# Do not reload during the reading.Before you leave the host
systemd Service Sandboxing Explained ends when the hostname in the prompt matches the hostname in the ticket. If it does not, you are on the wrong host. Stop. A command that succeeded on the wrong host is not progress.
The draft stays a draft until a person has read the names in it. A generator does not log into the host and does not know which disk is empty. You delete a line that names a host, a path, or an account you did not write down.
192.0.2.10/24, gateway 192.0.2.1, 198.51.100.0/24, 203.0.113.0/24, and 2001:db8::/32 are documentation. example.com is a documentation name. They belong in the note. They are not values you leave on a host because a draft included them.
prompt-for-this is a reminder that a secret is missing. It is not a password, a key, or a token you save in the ticket or in git. The real secret stays in the password store.
One change is the window. If two things move and the result is wrong, you will not know which one did it. The next change waits for its own page.
If the same step fails twice, stop for the day. The failure is the result. Adding a forum command beside a half-applied change produces a host nobody can rebuild. Restore the copy you took first.
A second person reads the hostname and the change aloud. If they cannot find them in the ticket, the note is not done. Silence is not agreement. Then leave the host alone.
This page is a planning guide. It is not a vendor manual, not an official standard, and not permission to touch a host you do not administer. You do not disable a firewall, AppArmor, or SELinux to make a check pass.
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