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 Superseded the 2026-05-30 port-knock design docs.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>
df332b59e6