df332b59e6
Viktor got locked out of the break-glass path (forgot the port-knock setup) and deleted the edge-router forwards, then asked to review and redesign it from scratch. Root cause of the lockout: the knock added no real security (key-only SSH is already brute-force-proof) and its only benefit — hiding the port — came at the cost of a circular dependency. The knock sequence lived only in in-cluster Vault, which is unreachable in the exact away/cold scenario break-glass exists for. So the unlock secret was unavailable precisely when needed. New model (self-contained, nothing to remember): plain key-only SSH on the Proxmox host's :52222, openly reachable. The edge router forwards WAN tcp/52222 -> 192.168.1.127:52222 (external port MUST equal internal on the TP-Link AX6000 - it rejects remaps; port 22 itself is reserved). The exposed port trusts only a dedicated break-glass key via `Match LocalPort` (a leak of any other root key does not grant internet access), rate-limited (iptables hashlimit) + fail2ban. - Removed knockd (package + config) and the legacy Synology SSH forward (ext 3333 -> .13:22, a needless WAN exposure the original plan wanted gone). - Fixed the fail2ban jail for Debian 13 (auth logs under sshd-session, not sshd - the stock journalmatch silently never banned). - Versioned the host config in scripts/ (it was applied ad-hoc, never committed) and recorded the deliberate Wave-1 "no public-IP" exception in security.md + .claude/CLAUDE.md. Superseded the 2026-05-30 port-knock design docs. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
31 lines
1.4 KiB
Text
31 lines
1.4 KiB
Text
# Break-glass SSH drop-in (redesigned 2026-06-11). Source of truth.
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# Deploy to the PVE host with:
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# scp scripts/sshd-10-breakglass.conf root@192.168.1.127:/etc/ssh/sshd_config.d/10-breakglass.conf
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# ssh root@192.168.1.127 'sshd -t && systemctl reload ssh'
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#
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# :22 = LAN admin, all of root's keys (default AuthorizedKeysFile).
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# :52222 = WAN-exposed break-glass. The edge router forwards WAN tcp/52222 ->
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# 192.168.1.127:52222 (external port MUST equal internal port on the
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# TP-Link AX6000 — it rejects remaps; port 22 itself is reserved).
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# The Match LocalPort block trusts ONLY the dedicated break-glass key
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# (authorized_keys.breakglass), so a leak of any other root key does
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# NOT grant internet access. Rate-limited by the BREAKGLASS iptables
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# chain + fail2ban. No port-knock.
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#
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# NOTE: the trailing `Match all` is REQUIRED. /etc/ssh/sshd_config has
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# `Include sshd_config.d/*.conf` near the top but a global `PermitRootLogin`
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# further down; without `Match all` resetting context, that later global
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# directive would be swallowed into the `Match LocalPort 52222` condition.
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Port 22
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Port 52222
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PasswordAuthentication no
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KbdInteractiveAuthentication no
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PubkeyAuthentication yes
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PermitRootLogin prohibit-password
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MaxAuthTries 3
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LoginGraceTime 20
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Match LocalPort 52222
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AuthorizedKeysFile /root/.ssh/authorized_keys.breakglass
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PermitRootLogin prohibit-password
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Match all
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