Files
config/etc/ssh/sshd_config.d/20-hardening.conf
T
bastien 55ede6f08c feat(install): security baseline: fail2ban, unattended-upgrades, sshd hardening
Always applied in the Linux block, no prompt, idempotent:
- install_fail2ban: fail2ban + nftables, etc/fail2ban/jail.d/local.conf.
  sshd jail reads the journal (backend systemd, works with or without
  auth.log) and bans the offender on every port, so the SSH port is
  irrelevant: the previous server's jail banned 22 while sshd listened
  on 337. 5 failures / 10 min / 1 h. Loopback + RFC1918 never banned.
- install_unattended_upgrades: package + 20auto-upgrades (the file
  dpkg-reconfigure writes, without the prompt).
- harden_sshd: sshd_config.d/20-hardening.conf (PermitRootLogin no,
  MaxAuthTries 3, LoginGraceTime 20), sshd -t gated: a rejected file is
  removed and the install continues with a warning. Auth methods, port
  and user lists untouched.
Docs: README table + step 13 + packages, CLAUDE.md layout.
2026-09-22 17:47:34 +02:00

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# sshd hardening, deployed by install.sh. Only settings that cannot lock anyone
# out: authentication methods, ports and user lists are left to the host.
PermitRootLogin no
MaxAuthTries 3
LoginGraceTime 20