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
sudo is how a named admin runs one command as another user. A safe rule names the person, the host, and the command. ALL for the command, and NOPASSWD on ALL, is the rule you are not writing.
The sudoers generator drafts a snippet. The syntax checker reads that snippet. Neither tool writes /etc/sudoers. When you later install a rule, visudo is the editor that refuses a broken file. This hour stops at the draft.
Do not give a web or service account a shell so that sudo is easier. Do not put a password in the snippet. The account that already administers the host stays. A second admin remains, so one broken rule does not lock the host.
The companion in the security desk is named in the plan as prose. This page does not replace that checklist. 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 person and the one command.
- Draft the snippet.
- Read it in the syntax checker.
- Reject NOPASSWD ALL.
- Do not copy it into /etc/sudoers during the reading.
- Keep a second admin written down.
Mistakes that outlive the command
How to Configure sudo Safely goes wrong in a small set of ways. The list is here so the ticket can forbid them before the window.
- ALL as the command.
- NOPASSWD on everything.
- A service account given a shell.
- Editing sudoers without a syntax check.
- A password in the snippet.
Decisions to write down
One decision for How to Configure sudo Safely: One person and one command. NOPASSWD is absent unless a ticket explains one command. The checker was used. The file was not installed during the reading. And a second admin still exists.
Checks before you call it done
Confirm this before you call the change done: The person is named. The command is named. The checker accepted the draft. No password is in the note. And sudoers was not edited yet. If one of those fails, stop.
# One user, one command.
# Not NOPASSWD ALL.
# Do not write /etc/sudoers during the reading.Before you leave the host
How to Configure sudo Safely 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.
Tools for this guide
These tools run in the browser on this site. They do not log into your machines.
Related pillar guides
More in this cluster
The pillar for this page, and the next published pages filed with it.
- Pillar: Linux File Permissions Explained
- How-To: How to Add Users in Linux
- How-To: How to Modify and Lock Linux Users
- Explainer: /etc/passwd and /etc/shadow Explained
Companion: Security: Linux Server Hardening Checklist.