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838132cd6b
Session captured: the FV outbound-NAT root cause and its diagnostic signature, the fv-ml1 dead man's switch, fleet identity/group/path conventions and the root:docker normalization, nh3-dev's ts-input reachability fix, ESPHome modernisation and the kb KB-search tool, and the Hermes bearer rotation release. Six new detail files. Tried-and-abandoned gains three: probing OPNsense endpoints by POSTing at them (which rebooted the FV firewall), advertising a /32 from nh3-dev, and the nh3-scale remote-site masquerade rules that fired but were not the fix. Housekeeping: 8 Recent-decisions entries archived to archival-memory.md, and 21 oversized inline entries split into detail files per the two-tier rule -- they had been sitting fully inline in the index, which is what the split exists to prevent. Two pointers to a detail file archived this run were repointed at archival-memory.md. The index is 389 lines, still over the ~300 soft cap. The archival guards stop it there: only 4 further entries are old enough to move and every one carries an open deferred-work pointer. An over-cap file that keeps live decisions beats a scannable one that lost a deferred call.
38 lines
1.7 KiB
Markdown
38 lines
1.7 KiB
Markdown
# `[2026-09-15]` nh3-dev unreachable from the mesh at its LAN address — ts-input anti-spoof
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`nh3-dev.nh3.internal` (10.100.10.50) failed from a mesh client while every
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other NH3 host worked. Not DNS, not routing.
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## Cause
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A host that runs Tailscale installs an anti-spoof rule:
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-A ts-input -s 100.64.0.0/10 ! -i tailscale0 -j DROP
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The fleet's subnet routers run `NoSNAT: true` with RFC1918 exempted from
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masquerade — **deliberate source preservation, and a departure from Tailscale's
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own `--snat-subnet-routes=true` default**. So a mesh client's packet reached
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nh3-dev's `ens18` still sourced `100.64.x` and died there, silently. Every NH3
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host that does **not** run Tailscale was unaffected, which is what made it look
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like a name-resolution fault.
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Control that settled it: `nh3-pve` (10.100.250.60) is off-link, needs a gateway
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hop, and works fine — it has no Tailscale and therefore no `ts-input` chain.
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## Fix
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One rule on nh3-scale (CT 107), above the RFC1918 RETURNs in
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`/usr/local/sbin/mesh-exit-masq.sh`: `-d 10.100.10.50/32 -j MASQUERADE`. Commit
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`9dbd829`, canonical copy `servers/nh3-pve/mesh-exit-masq.sh`.
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## ⚠ Do NOT instead advertise the /32 from nh3-dev
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Tried the same day and it black-holed nh3-dev from ESH, Anaheim, FV and Irvine
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while leaving its own LAN and the internet up. `ip rule` there puts `lookup 52`
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at priority 5270, ahead of `main` at 32766; becoming a subnet router let table
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52 capture cross-site traffic a `RouteAll: false` node has no accepted route
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for. ⚠ **A one-host check against its own LAN passes cleanly** — test all four
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sites. Same family as the 2026-09-06 accept-routes incident.
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Related: [[2026-09-15-fv-cross-site-snat]]
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