SEC.01

The playbook

The run starts read-only: the recon probes decide what happens next. The steps that follow are adapted to the distribution and state found — a real machine is rarely clean.

1. 01recondistro and OpenSSH version (KbdInteractiveAuthentication ≥ 8.7)
2. 02reconthe effective SSH config (port, root, password, key location)
3. 03recondoes sshd_config include sshd_config.d/? which drop-ins exist (50-cloud-init.conf may re-enable passwords)?
4. 04reconwhich accounts have authorized keys and which are sudoers (no key → DO NOT turn off passwords)
5. 05reconTOTP 2FA in place? (then keep KbdInteractiveAuthentication)
6. 06reconunit name: ssh (Debian/Ubuntu), sshd (RHEL), ssh.socket (socket activation)
7. 07reconis the SSH config valid before touching it?
8. 08actBack up sshd_configverify
9. 09actInclude sshd_config.d (only if the Include is missing)verify
10. 10actTurn off root password login + password logindestructiveverify
11. 11actCheck the effective config before reloadingverify
12. 12actReload sshd (without dropping sessions)destructiveverify

SEC.02

What it verifies

Each step ships its own check. The run only moves on when the check passes, so what the recipe reports as done is what is actually on the server.

1. 01verifyBack up sshd_configVerified byls -1 /etc/ssh/sshd_config.bak.* | tail -1
2. 02verifyInclude sshd_config.d (only if the Include is missing)Verified bygrep -cE '^\s*Include\s+/etc/ssh/sshd_config.d/' /etc/ssh/sshd_config && sshd -t && echo ok
3. 03verifyTurn off root password login + password loginVerified bysshd -t 2>&1 && echo ok
4. 04verifyCheck the effective config before reloadingVerified bysshd -T | grep -Ei '^(permitrootlogin|passwordauthentication) '
5. 05verifyReload sshd (without dropping sessions)Verified bysystemctl is-active ssh.service sshd.service ssh.socket 2>/dev/null | grep -c '^active'

SEC.03

Guardrails

Non-negotiable instructions the run must respect, whatever it finds on the server.

SEC.04

Variables

What you choose before launching — the recipe fills in the rest.

SEC.05

How a recipe runs in Servor

Servor is zero-knowledge: the platform cannot execute anything on its own. When you launch this recipe, a run reads the reconnaissance, plans the steps and asks for your approval. Each approved command is signed by your browser — with a key the server never sees — then relayed verbatim to the agent, which verifies the signature locally before executing.

SEC.06

Deploy on Servor button

Maintain Harden SSH or a project that needs it? Put this button in your README or on your site: one click and your users install it on their own server.

SEC.07

More security recipes

1. 01fail2banfail2ban with the SSH jail on the right port, active and verified.
2. 02UFW firewallUFW: denies incoming by default, allows the real SSH port + chosen ports, with a safety net. Destructive: keeps SSH open.
3. 03Automatic security updatesEnables automatic security updates: unattended-upgrades (Debian/Ubuntu) or dnf-automatic (RHEL/Fedora).
4. 04CrowdSecCrowdSec collaborative IPS, SSH collections and firewall bouncer.
5. 05ClamAVClamAV antivirus with signatures kept up to date, optional daemon.