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| Author | SHA1 | Date | |
|---|---|---|---|
  jakman85andClaude Opus 5
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b258e47aa6 |
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@@ -73,7 +73,7 @@ spec:
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- name: FTLCONF_dns_rateLimit_count
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value: '0'
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- name: FTLCONF_misc_dnsmasq_lines
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value: local-ttl=60;address=/${BASE_DOMAIN}/${GATEWAY_VIP};address=/unifi.${BASE_DOMAIN}/${UNIFI_L4_VIP};address=/crafty-mc.${BASE_DOMAIN}/${CRAFTY_L4_VIP};address=/pihole-dns.${BASE_DOMAIN}/${PIHOLE_DNS_VIP};address=/plex-vip.${BASE_DOMAIN}/${PLEX_L4_VIP}
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value: address=/${BASE_DOMAIN}/${GATEWAY_VIP};address=/unifi.${BASE_DOMAIN}/${UNIFI_L4_VIP};address=/crafty-mc.${BASE_DOMAIN}/${CRAFTY_L4_VIP};address=/pihole-dns.${BASE_DOMAIN}/${PIHOLE_DNS_VIP};address=/plex-vip.${BASE_DOMAIN}/${PLEX_L4_VIP}
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- name: FTLCONF_webserver_api_password
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valueFrom:
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secretKeyRef:
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+1
-32
@@ -143,39 +143,8 @@ env:
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# resolved to the Gateway VIP and a connect to :32400 there returned http=000. That is a silent
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# failure: the Plex web UI on plex.${BASE_DOMAIN} keeps working through the Gateway on 443 while
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# every client that takes the ADVERTISED connection cannot reach the server at all.
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#
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# ── local-ttl=60 — THE SPLIT-HORIZON ANSWER MUST BE CACHEABLE ────────────────────────────────
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# MEASURED 2026-10-18, diagnosing "DNS flapping between the cluster ingress and the public IP":
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#
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# dig home.keithjackson.dev @192.168.2.23 (pihole) -> 192.168.2.20 TTL=0
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# dig home.keithjackson.dev @1.1.1.1 (public) -> wan.home.keithjackson.dev TTL=300
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# dig home.keithjackson.dev @192.168.2.1 (router) -> wan.... TTL=153 -> 148 -> 143
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#
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# dnsmasq answers `address=` entries with **TTL 0** unless told otherwise, and that is the whole
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# bug. The SOHO router forwards LAN queries to PiHole and CACHES the result, so:
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# * the CORRECT answer is UNCACHEABLE (TTL 0) -- the router must re-query PiHole on every
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# single lookup, which is maximum exposure to any momentary gap; while
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# * the WRONG answer is CACHEABLE FOR 5 MINUTES -- the instant the router falls back to its
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# upstream (standard forwarder behaviour when the forward target does not answer) it latches
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# the public WAN address and serves it to EVERY LAN CLIENT for the public record's 300s TTL.
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# The decrementing TTL on the router's reply above is the proof it caches rather than forwarding
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# live. So ONE sub-second PiHole gap -- a pod restart, an L2 announcement lease moving, an ARP
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# flap, a kured node reboot -- becomes FIVE MINUTES of the whole house resolving to the WAN IP.
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# That asymmetry, not the gap, is why this is visible as "flapping" rather than a blip.
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#
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# 60s is a deliberate floor, not a tuning knob: long enough to ride out a pod restart and a lease
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# re-election (both seconds), short enough that a genuine VIP change still propagates inside a
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# minute. These VIPs are pinned by name (`lbipam.cilium.io/ips`) and effectively static, so the
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# propagation cost is theoretical while the flap it prevents is measured. If flaps persist across
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# LONGER outages, raising this toward the public record's 300 would cover them -- at the cost of
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# the same delay on a real change. It does NOT help when PiHole is down longer than the TTL: the
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# cache expires, the router falls back, and the public answer latches again. That is a real
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# outage, and the fix for it is PiHole availability, not DNS caching.
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#
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# Applies to every `address=` reply below (dnsmasq: local-ttl governs replies made from
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# configuration, /etc/hosts and DHCP leases), so one directive covers all five names.
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- name: FTLCONF_misc_dnsmasq_lines
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value: "local-ttl=60;address=/${BASE_DOMAIN}/${GATEWAY_VIP};address=/unifi.${BASE_DOMAIN}/${UNIFI_L4_VIP};address=/crafty-mc.${BASE_DOMAIN}/${CRAFTY_L4_VIP};address=/pihole-dns.${BASE_DOMAIN}/${PIHOLE_DNS_VIP};address=/plex-vip.${BASE_DOMAIN}/${PLEX_L4_VIP}"
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value: "address=/${BASE_DOMAIN}/${GATEWAY_VIP};address=/unifi.${BASE_DOMAIN}/${UNIFI_L4_VIP};address=/crafty-mc.${BASE_DOMAIN}/${CRAFTY_L4_VIP};address=/pihole-dns.${BASE_DOMAIN}/${PIHOLE_DNS_VIP};address=/plex-vip.${BASE_DOMAIN}/${PLEX_L4_VIP}"
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# THE ADMIN PASSWORD, previously the ONE operator-set value declared nowhere. Sourced from
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# apps/wave-0/pihole-bootstrap-secret.sops.yaml (SOPS/age, same wave => same reconcile), which
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# carries the full rationale and the measurement that found it.
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@@ -0,0 +1,198 @@
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---
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date: 2026-10-17
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branch: fix/vpn-ingress-l2-lease-collision
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title: "WITHDRAWN: a node CAN reach a VIP it announces. My L2-lease diagnosis was wrong"
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---
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## What changed
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**This branch previously proposed a fix. That fix has been reverted in full. The diagnosis behind it
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was wrong.** What is left is documentation of what was actually measured, so the wrong conclusion is
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not re-derived — it is very easy to re-derive from `ip neigh` alone.
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### The claim, and how it died
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The earlier version of this entry claimed: *a node cannot reach a LoadBalancer VIP whose Cilium L2
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announcement lease it holds itself* — the announcer does not answer its own ARP request, the
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neighbour entry settles at `FAILED`, and packets to that VIP die before leaving the node. Because
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`platform/vpn-ingress` runs WireGuard on `hostNetwork` and MASQUERADEs remote clients to the node's
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own address, a VPN client was said to inherit that. The fix labelled the forwarded node and excluded
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that label from announcing, with two alerts and four promtool tests behind it.
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The claim makes a sharp prediction. After today's UPS power-cycle **all eight** `cilium-l2announce-*`
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leases are held by `k3s-prod-1` (gateway, pihole tcp+udp, crafty tcp+udp, unifi tcp+udp, plex) —
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the extreme case. The prediction was therefore that `k3s-prod-1` should reach **none** of the five
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VIPs and the other two nodes should reach **all**.
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**The prediction failed.** Measured from the host netns of the `wireguard` pod on each node:
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| | `k3s-prod-1` (holds all 8) | `k3s-prod-2` / `-3` (hold none) |
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|---|---|---|
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| `ip neigh show 192.168.2.20` | `FAILED`, no lladdr | `lladdr bc:e9:2f:7e:c4:a6 REACHABLE` |
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| `curl -k https://192.168.2.20/` | **`200` in 18 ms** | `200` in 13–40 ms |
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| `nc -z 192.168.2.20 443` | **OK** | OK |
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| `192.168.2.22:25565`, `.23:53`, `.24:32400` | **all OK / `200`** | all OK / `200` |
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| `192.168.2.21:8443` | FAIL | **FAIL** (both) |
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The asserted **cause is still present** today — `FAILED` on the holder, for all five VIPs — while the
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asserted **effect is absent**. That is sufficient to falsify the causal claim without having to
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explain anything else. The ARP asymmetry is real and reproducible; it is also **inert**.
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### Why it is inert
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No traffic path resolves a LoadBalancer VIP by ARP:
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* `cilium-dbg status --verbose` reports `KubeProxyReplacement: True [eno1 …, wg0 10.90.0.1]` and
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`Masquerading: BPF [eno1, wg0]` (Cilium v1.20.1, TCX attach, tunnel/vxlan). Cilium's LB datapath
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is attached to **`wg0` as well as `eno1`**, so a remote client's packet arriving on `wg0` for a VIP
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is DNAT'd **in BPF, before any route or neighbour lookup for the VIP**.
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* `cilium-dbg service list` programs `192.168.2.20:443 => 127.0.0.1:13606` — the shared Gateway's
|
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backend is a **node-local** Envoy socket, so every node serves that VIP without a LAN packet.
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* Host-originated traffic is socket-LB'd (`Socket LB: Enabled`, `bpf-lb-sock-hostns-only: true`),
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which is why `curl` succeeds on the holder. Discriminator: a real service port connects while a
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bogus one (`nc -z 192.168.2.20 9999`) fails, identically on all three nodes — service-aware DNAT,
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not wire traffic.
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### The two probes that misled me
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Both were cited as evidence in the previous version of this entry.
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* **`ip neigh` on its own.** `FAILED` on the holder is permanent and harmless, and is also a probing
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artefact: VIPs answer no ICMP, so a `ping` leaves a failed entry whether or not anything is wrong.
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* **`curl --interface wg0`.** The previous entry used this as the control that ruled out a
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host-netns artefact. It is not a control: it fails (`rc=28`) from **all three** nodes, including
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the two whose ARP for the VIP resolves perfectly. It is uncorrelated with lease holding, so it
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discriminates nothing.
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**The deeper error:** a MASQUERADEd client's packets are **forwarded** (netfilter `FORWARD`, then
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routing); everything runnable from the pod is **socket-originated**. Different hooks. A host-netns
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probe cannot measure the forwarded path in either direction — it reports success where the forwarded
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path might fail, and `--interface wg0` reports failure where it does not. Sharing a netns is not
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sharing a hook, and that is the assumption the original diagnosis rested on.
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### Files
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Reverted to `origin/main`: `platform-config/cilium/l2-announcement-policy.yaml`,
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`infra/ansible/roles/node_baseline/{defaults,tasks}/main.yml`,
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`infra/ansible/inventory/group_vars/k3s_prod/vars.yml`, `platform/monitoring/alerts.yaml`,
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`platform/monitoring/kube-prometheus-stack.yaml`, `runbooks/kustomization.yaml`. Deleted:
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`platform/monitoring/tests/vpn-ingress-l2.test.yaml`, `runbooks/vpn-ingress-l2-collision.md`.
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Kept, rewritten from scratch:
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* **`platform/vpn-ingress/README.md`** — two measured sections: the L2 table above with why it is
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inert and which probes lie, and the internet-egress facts below.
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* **`runbooks/vpn-remote-access.md`** — a triage section for the reported symptom ("LAN and cluster
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work, internet does not") that works outwards from the client profile, and a short section saying
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the L2 lease is a dead end, with the unifi `.21` note.
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**Nothing in `platform/vpn-ingress` or `infra/vpn-ingress` changed behaviourally. No code fix is
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proposed by this branch any more.**
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### The internet-routing report: no server-side fix was needed, and none was made
|
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The brief's prior was that `new-peer.sh` renders a split tunnel and that the operator wants a full
|
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one, to be added as a documented option. **That prior does not match the tree.** `new-peer.sh` has
|
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emitted `AllowedIPs = 0.0.0.0/0` **by default since the component's first commit** (`f92707f`,
|
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2026-10-05, confirmed with `git log -S`); `--split` is the opt-in, and
|
||||
`runbooks/vpn-remote-access.md:252-253` already documents both forms. So there is no full-tunnel
|
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feature to add, and adding a `WG_FULL_TUNNEL` knob would be a second switch for a default that
|
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already exists. **I deliberately shipped no code change here** — writing one would have meant
|
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inventing a fix for a symptom I could not reproduce (see below).
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The server side was measured end to end and is capable and correct, so the cause is in the client
|
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profile or the client. The triage section names the two candidates that fit the symptom exactly —
|
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a `--split` profile, and the IPv4-only `AllowedIPs` letting a dual-stack client prefer AAAA and
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leak public traffic outside the tunnel — each with a one-line test that settles it.
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## What I verified
|
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Measured live against prod, `kubectl --context k3s-prod --request-timeout=15s`, read-only, on
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2026-10-17:
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|
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* **The lease distribution.** All eight `cilium-l2announce-*` leases held by `k3s-prod-1`
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(`.spec.holderIdentity`). The brief's observation reproduced; it had not moved again.
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* **The falsification, in full**, as tabulated above: 3 nodes x 5 VIPs, `ip neigh` + `nc -z` + a
|
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real `curl` for each. The holder reaches four of five VIPs; `.21` fails from everywhere.
|
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* **The socket-LB discriminator.** Real service port OK, bogus port FAIL, identically on all three
|
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nodes — so the successes are service-aware DNAT, not wire delivery.
|
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* **`curl --interface wg0` fails on all three nodes**, including non-announcing ones with
|
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`REACHABLE` neighbour entries. This is the measurement that destroys the original control.
|
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* **The datapath facts** quoted above from `cilium-dbg status --verbose` and
|
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`cilium-dbg service list` on `cilium-55jv8` (`k3s-prod-1`), plus `cilium-config`:
|
||||
`kube-proxy-replacement=true`, `enable-l2-announcements=true`, `enable-bpf-masquerade=true`,
|
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`routing-mode=tunnel`, `devices=` (empty, auto-detected). Cilium `v1.20.1` on all three.
|
||||
* **The VIP is not a local address and routes on-link.** `ip route get 192.168.2.20` →
|
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`dev eno1 src 192.168.2.10` on the holder; nothing in `table local`; `ip -4 addr` shows no VIP.
|
||||
So the 200 is not loopback delivery by the host stack — it is BPF.
|
||||
* **The internet path, server side, on all three nodes:** `/proc/sys/net/ipv4/ip_forward` = `1`
|
||||
(read, never written); `iptables -t nat -S POSTROUTING` carries
|
||||
`-s 10.90.0.0/24 ! -o wg0 -j MASQUERADE`; the preceding `CILIUM_POST_nat` chain is **empty with 0
|
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packets**, so it cannot short-circuit that rule; `FORWARD -i wg0` and `-o wg0` ACCEPT both
|
||||
present; `default via 192.168.2.1 dev eno1 onlink` intact; `ip route get 1.1.1.1` resolves via it;
|
||||
`curl http://1.1.1.1/` returns `301` from each node.
|
||||
* **The PIA / egress-gateway answer.** `platform/vpn-egress/egress-steering.yaml` selects by
|
||||
`podSelector` on `egress-class: vpn`; `platform/vpn-ingress/daemonset.yaml:130` labels this pod
|
||||
`egress-class: internet`; `tun0` exists on **`k3s-prod-3` only** (`10.150.192.3/18`), absent on
|
||||
`-1` and `-2`. So a full tunnel egresses the **house WAN**, and a client's apparent address is the
|
||||
home WAN IP, not PIA's.
|
||||
* **PiHole resolves public names** — `nslookup google.com 192.168.2.23` from the pod returned
|
||||
`142.250.113.138`.
|
||||
* **No client is connected, and none has been since the power-cycle.** `wg show wg0` lists the one
|
||||
enrolled peer (`10.90.0.2/32`) with **no endpoint and no handshake** on all three nodes, and both
|
||||
`FORWARD -i wg0` and the `MASQUERADE` rule read **0 packets / 0 bytes** on all three. The
|
||||
`wireguard` pods restarted 153 min ago (2 restarts, 11d old), which reset the counters.
|
||||
* **The full-tunnel default's age**, from `git log -S` on `new-peer.sh`: introduced in `f92707f`
|
||||
(2026-10-05) and never changed.
|
||||
* **The branch rebased cleanly** onto `origin/main` (`1a0b208`, PR #70 merged) with no conflicts.
|
||||
|
||||
## What I did NOT verify
|
||||
|
||||
* **THE FORWARDED PATH IS STILL UNMEASURED, in both directions.** No client is connected, so I could
|
||||
not test what a real remote client does, and — as established above — **no probe runnable from the
|
||||
pod can substitute for it**. Specifically I did **not** prove that a forwarded client packet to a
|
||||
VIP is DNAT'd by Cilium's `wg0` program. That inference rests on `cilium-dbg` listing `wg0` as a
|
||||
LB device plus the node-local Gateway backend, not on an observed client packet. **It is the one
|
||||
remaining way the withdrawn diagnosis could be partly right** — if `wg0` BPF were somehow not in
|
||||
the forwarded path, forwarded traffic would need ARP and would die on the holder. I judge this
|
||||
unlikely but it is unproven. *To close it: connect a client, then from the node whose `wg show`
|
||||
shows the peer endpoint, watch `FORWARD -i wg0` and the `MASQUERADE` counters move while the
|
||||
client loads a cluster app — and repeat it on a node that holds leases and one that does not.*
|
||||
* **WHICH NODE THE ROUTER FORWARDS `udp/51820` TO IS UNDETERMINABLE RIGHT NOW**, for the same
|
||||
reason. **I need a client connected** to learn it; the router is unreadable from the cluster.
|
||||
* **I cannot reproduce or explain the 2026-10-08 measurements.** That entry recorded `nc -z` TCP
|
||||
failures correlated with lease holding across 15 node x VIP pairs. Today the same test passes.
|
||||
My leading hypothesis is **stale or incorrectly-programmed BPF LB state on `k3s-prod-1`**,
|
||||
rebuilt by today's full power-cycle — which would make the lease correlation coincidental. A
|
||||
competing hypothesis is that Cilium had not auto-detected `wg0` then (`devices` is empty, and
|
||||
`wg0` is created by this DaemonSet after Cilium starts). **Both are unproven, and neither is
|
||||
needed for the falsification** — the asserted cause is present today without its effect. I did not
|
||||
retro-measure anything, and I did not read Cilium's source or issue tracker.
|
||||
* **The operator's report cannot be a description of "right now."** No client has connected since
|
||||
the power-cycle (0 forwarded packets, no handshake on any node), so "clients can reach cluster
|
||||
services and the LAN but not the internet" must describe a session before the power-cycle or one
|
||||
that has since dropped. **I did not establish when it was observed, or with which profile.**
|
||||
* **THE INTERNET ROOT CAUSE IS NOT DIAGNOSED.** I proved the server side is *capable*; I did **not**
|
||||
find the fault, and I shipped no fix for it. The two candidates in the triage section (a
|
||||
`--split` profile; IPv6 preference leaking outside an IPv4-only `AllowedIPs`) are **reasoned, not
|
||||
measured**. *What I need:* the `AllowedIPs` line from the client's own profile — that one line
|
||||
decides split vs full and halves the search — and a connected client for step 2.
|
||||
* **Whether `--split` was in fact used for the enrolled peer.** The profile holds a private key and
|
||||
lives only on the operator's machine and the device; it is not in the repo, and I did not look for
|
||||
it. Server-side `AllowedIPs` is a `/32` source filter and says nothing about the client's routing.
|
||||
* **Whether `MTU = 1420` holds on a full-tunnel WAN path.** Not measured, and not measurable without
|
||||
a client. It is the standard 1500 − 60; a client behind PPPoE or CGNAT with a smaller path MTU
|
||||
would see large transfers hang while small requests succeed. The runbook's existing MTU note
|
||||
(drop to 1280) already covers the remedy.
|
||||
* **Adding `::/0` to `AllowedIPs` is untested advice.** The triage section offers it to blackhole
|
||||
IPv6 rather than leak it, and states that the tunnel has no IPv6 egress. I did not try it on a
|
||||
client, and I do not know how each WireGuard client behaves when handed an IPv6 route on an
|
||||
interface with no IPv6 address.
|
||||
* **`192.168.2.21:8443` (unifi) fails from all three nodes**, as it did on 2026-10-08 — a separate,
|
||||
pre-existing fault. Not investigated, not addressed, and now recorded in the runbook as such.
|
||||
* **No runtime conformance.** `vars.CLUSTER_AVAILABLE` is still unset, so the gate proves the L0/L1
|
||||
offline subset only. Nothing above is covered by a test that runs in CI.
|
||||
* **Nothing was applied, and nothing needs to be.** The branch is now documentation-only, so there
|
||||
is no Flux reconcile, Ansible run or `kubectl` step to perform after merge. I ran no mutating
|
||||
`kubectl`, `flux` or Ansible, and did not run `new-peer.sh` (it mints key material).
|
||||
* I did not re-measure branch protection, runner state, or any other platform claim (CLAUDE.md §2b).
|
||||
@@ -1,82 +0,0 @@
|
||||
---
|
||||
date: 2026-10-18
|
||||
branch: fix/pihole-local-ttl
|
||||
title: "The split-horizon answer was uncacheable while the wrong answer cached for 5 minutes"
|
||||
---
|
||||
|
||||
## What changed
|
||||
|
||||
The operator reported DNS "flapping between the cluster ingress and the router (public IP)".
|
||||
PiHole was not at fault — both replicas answer correctly and consistently. The bug is an
|
||||
**asymmetry in cacheability** that we created.
|
||||
|
||||
Measured on prod 2026-10-18:
|
||||
|
||||
```
|
||||
dig home.keithjackson.dev @192.168.2.23 (pihole) -> 192.168.2.20 TTL=0
|
||||
dig home.keithjackson.dev @1.1.1.1 (public) -> wan.home.keithjackson.dev TTL=300
|
||||
dig home.keithjackson.dev @192.168.2.1 (router) -> wan.... TTL=153 -> 148 -> 143
|
||||
```
|
||||
|
||||
dnsmasq answers `address=` entries with **TTL 0** unless told otherwise. The SOHO router forwards
|
||||
LAN queries to PiHole and **caches** the result — the decrementing TTL above is the proof it caches
|
||||
rather than forwarding live. So:
|
||||
|
||||
* the **correct** answer is **uncacheable** (TTL 0): the router must re-query PiHole on *every*
|
||||
lookup, which is maximum exposure to any momentary gap;
|
||||
* the **wrong** answer is **cacheable for 300s**: the instant the router falls back to its upstream
|
||||
(standard forwarder behaviour when the forward target does not answer) it latches the public WAN
|
||||
address and serves it to **every LAN client** for five minutes.
|
||||
|
||||
So **one sub-second PiHole gap becomes five minutes of the whole house resolving to the WAN IP** —
|
||||
then it expires, the router re-queries PiHole, gets TTL 0 again, and is immediately re-exposed.
|
||||
That asymmetry, not the gap itself, is why this is visible as flapping rather than a blip.
|
||||
|
||||
Fix: `local-ttl=60` prepended to `FTLCONF_misc_dnsmasq_lines` in `catalog/pihole.yaml`, so the
|
||||
private answer is cacheable and a short gap is invisible to clients. `apps/wave-0/pihole.yaml`
|
||||
regenerated with the canonical render command.
|
||||
|
||||
## What I verified
|
||||
|
||||
* **PiHole is NOT the fault.** Both replicas, queried directly by pod IP, answer `192.168.2.20`;
|
||||
the VIP returned it 6/6; this workstation 8/8. DHCP hands out only `192.168.2.23`.
|
||||
* **The router caches rather than forwards live** — three successive queries returned TTL 153, 148,
|
||||
143 (decrementing), which a pure forwarder could not do.
|
||||
* **The TTL asymmetry**, as quoted above: 0 from PiHole, 300 from public DNS.
|
||||
* **The router does answer DNS and returns the public chain** (`wan.home.keithjackson.dev` → the WAN
|
||||
address), so a fallback always has a wrong answer available.
|
||||
* **`local-ttl` is the right directive**: dnsmasq applies it to replies made from configuration,
|
||||
`/etc/hosts` and DHCP leases, which covers all five `address=` names with one directive. It is a
|
||||
standalone option, not a sub-field of `address=`, so prepending it to the `;`-separated
|
||||
`FTLCONF_misc_dnsmasq_lines` list is syntactically correct.
|
||||
* **The render is clean and scoped**: `catalog/render.py --all catalog -o apps --wave-layout
|
||||
--no-image-automation` (the canonical command `ci/render-golden.sh` asserts against, and
|
||||
deliberately **not** `--emit-waves`) changed exactly two files — `catalog/pihole.yaml` and
|
||||
`apps/wave-0/pihole.yaml` — and the rendered diff is the single `local-ttl=60;` prefix.
|
||||
|
||||
## What I did NOT verify
|
||||
|
||||
* **UNAPPLIED.** Nothing has been reconciled, so I have not observed PiHole serving a non-zero TTL,
|
||||
nor the router caching the private answer, nor the flap stopping. **Verify after merge with
|
||||
`dig home.keithjackson.dev @192.168.2.23` (expect `TTL=60`, not 0) and then the same query at the
|
||||
router (expect `192.168.2.20` with a decrementing TTL, not `wan.…`).**
|
||||
* **I did not confirm that PiHole/FTL accepts `local-ttl` via `FTLCONF_misc_dnsmasq_lines`.** The
|
||||
directive is valid dnsmasq and the field is a passthrough, but `catalog/pihole.yaml`'s own header
|
||||
records that FTL has previously written a bogus line into `dnsmasq.conf` and reported "0 invalid"
|
||||
— so a malformed passthrough fails *silently*. If the TTL is still 0 after merge, that is the
|
||||
cause, not this reasoning. Check the pod's `/etc/pihole/dnsmasq.conf`.
|
||||
* **60s is chosen, not derived.** Long enough for a pod restart and a lease re-election (both
|
||||
seconds); it does **nothing** for an outage longer than the TTL, where the cache expires and the
|
||||
public answer latches again. That is a real availability problem, not a caching one.
|
||||
* **This does not remove the trigger.** `192.168.2.23` is served by **two** LoadBalancer Services
|
||||
(`pihole-dns-tcp`, `pihole-dns-udp`) with **two independently-elected L2 announcement leases**, so
|
||||
two nodes can ARP for the same address at once — they sat on different nodes earlier the same day
|
||||
(tcp on prod-2, udp on prod-1). The same pattern applies to crafty (`.22`) and unifi (`.21`).
|
||||
Merging each pair into one mixed-protocol Service would remove the class; the operator has parked
|
||||
that decision, and it is deliberately **not** in this change.
|
||||
* **Client-side bypasses are unexamined.** A device with its own resolver, or a browser with
|
||||
DNS-over-HTTPS, bypasses PiHole entirely and always gets the public answer; this fix cannot help
|
||||
there. Only this one workstation's resolver chain was inspected.
|
||||
* **No alert fires if the split-horizon answer regresses to the public address.** Nothing probes
|
||||
`home.keithjackson.dev` from a LAN vantage point and compares it against `${GATEWAY_VIP}`, so the
|
||||
next recurrence would again be found by a human noticing. That gap is not closed here.
|
||||
@@ -186,6 +186,86 @@ right way; one was a defect in my own manifest.
|
||||
| Is the image's **iptables** backend compatible with the host's? | **Yes — both nft.** The image ships `iptables v1.8.13 (nf_tables)` via `xtables-nft-multi`, and Debian 13 is nf_tables. This was the documented worst fear (rules silently landing in a table the kernel does not consult); it is closed. |
|
||||
| Can the pod set **`net.ipv4.ip_forward`**? | **No, and it must not try.** `/proc/sys` is mounted **read-only** under `hostNetwork` (`proc /proc/sys proc ro,…`), because those are the host's globals; `sysctl -w` fails with EPERM whatever the capabilities. A failed `PostUp` is fatal to `wg-quick`, so this one line took the whole tunnel down. The node already has it set to `1`; the init container now **verifies** rather than writes. |
|
||||
|
||||
## Measured on prod, 2026-10-17 — L2 announcement does NOT affect what a client can reach
|
||||
|
||||
A change was proposed (PR #69) on the belief that **a node cannot reach a LoadBalancer VIP whose
|
||||
Cilium L2 announcement lease it holds**, and that the VPN node therefore had to be excluded from
|
||||
announcing. **That belief is wrong, and the change was withdrawn.** The half of it that is true is
|
||||
real but inert, and the distinction matters enough to record, because the wrong version is very
|
||||
easy to re-derive from `ip neigh` alone.
|
||||
|
||||
Measured with all **eight** `cilium-l2announce-*` leases held by `k3s-prod-1` — the extreme case,
|
||||
after the UPS power-cycle — from the host netns of the `wireguard` pod on each node:
|
||||
|
||||
| | `k3s-prod-1` (holds all 8) | `k3s-prod-2` / `-3` (hold none) |
|
||||
|---|---|---|
|
||||
| `ip neigh show 192.168.2.20` | `FAILED` (no lladdr) | `lladdr bc:e9:2f:7e:c4:a6 REACHABLE` |
|
||||
| `curl -k https://192.168.2.20/` | **`200`, 18 ms** | `200`, 13–40 ms |
|
||||
| `nc -z 192.168.2.20 443` | **OK** | OK |
|
||||
| plex `192.168.2.24:32400` | **`200`** | `200` |
|
||||
|
||||
So the announcer really does **not** answer its own ARP request — that part of the observation is
|
||||
reproducible. It changes nothing, because **no traffic path resolves a LoadBalancer VIP by ARP**:
|
||||
|
||||
* `cilium-dbg status --verbose` reports `KubeProxyReplacement: True [eno1 …, wg0 10.90.0.1]` and
|
||||
`Masquerading: BPF [eno1, wg0]`. Cilium's LB datapath is attached to **`wg0` as well as `eno1`**,
|
||||
so a remote client's packet arriving on `wg0` for a VIP is DNAT'd to a backend **in BPF, before
|
||||
any route or neighbour lookup for the VIP happens**.
|
||||
* `cilium-dbg service list` on `k3s-prod-1` programs `192.168.2.20:443 => 127.0.0.1:13606` — the
|
||||
shared Gateway's backend is a **node-local** Envoy socket. Every node can serve that VIP without
|
||||
a packet crossing the LAN at all.
|
||||
* Host-originated traffic is socket-LB'd (`Socket LB: Enabled`, `bpf-lb-sock-hostns-only: true`),
|
||||
which is why `curl` succeeds on the lease holder despite `FAILED`. The discriminator: a **real**
|
||||
service port connects, a **bogus** one (`nc -z 192.168.2.20 9999`) fails, on all three nodes —
|
||||
that is service-aware DNAT, not wire traffic.
|
||||
|
||||
**Two tests that look like proof and are not.** Both were used to support the withdrawn diagnosis:
|
||||
|
||||
* **`ip neigh` on its own.** `FAILED` on the holder is permanent and harmless. It is also an
|
||||
artefact of probing: VIPs answer no ICMP, so a `ping` leaves a failed entry behind whether or not
|
||||
anything is wrong.
|
||||
* **`curl --interface wg0`.** This fails (`rc=28`, timeout) from **all three** nodes, including the
|
||||
two whose ARP for the VIP resolves perfectly. It is not correlated with lease holding, so it
|
||||
discriminates nothing — and it is not the client path either (see below).
|
||||
|
||||
**Why neither probe can see the client path.** A MASQUERADEd remote client's packets are
|
||||
**forwarded** — netfilter `FORWARD`, then routing — whereas everything runnable from the pod is
|
||||
**socket-originated**. The two traverse different hooks, so a host-netns probe cannot measure the
|
||||
forwarded path in either direction: it reports success where the forwarded path might fail, and
|
||||
`--interface wg0` reports failure where it does not. **The forwarded path can only be measured with
|
||||
a client actually connected**, by watching the `FORWARD -i wg0` and `POSTROUTING … MASQUERADE`
|
||||
counters move.
|
||||
|
||||
## Measured on prod, 2026-10-17 — where a full tunnel's internet traffic actually egresses
|
||||
|
||||
`new-peer.sh` has emitted a **full tunnel** (`AllowedIPs = 0.0.0.0/0`) **by default since the
|
||||
component's first commit**; `--split` is the opt-in for LAN-only. There is no full-tunnel feature
|
||||
to add. The server side was checked end to end and is **capable and correct** — if a full-tunnel
|
||||
client cannot reach the internet, nothing in the list below is the reason:
|
||||
|
||||
| checked | result on all three nodes |
|
||||
|---|---|
|
||||
| `net.ipv4.ip_forward` (read from `/proc/sys`, never written) | `1` |
|
||||
| `iptables -t nat -S POSTROUTING` | carries `-s 10.90.0.0/24 ! -o wg0 -j MASQUERADE` — NATs to **any** outbound interface, so internet NAT needs no change |
|
||||
| `CILIUM_POST_nat`, which precedes it in the chain | **empty, 0 packets** — it cannot short-circuit the MASQUERADE |
|
||||
| `iptables -L FORWARD` | `-i wg0` and `-o wg0` ACCEPT both present |
|
||||
| default route | `default via 192.168.2.1 dev eno1 onlink`, intact |
|
||||
| node's own internet reachability | `http://1.1.1.1/` returns `301` |
|
||||
|
||||
**A full tunnel egresses the HOUSE WAN, not PIA.** This was the trap worth checking, and it is
|
||||
closed: `platform/vpn-egress/egress-steering.yaml`'s `CiliumEgressGatewayPolicy` selects by
|
||||
`podSelector` on `egress-class: vpn`, and this DaemonSet is deliberately labelled
|
||||
`egress-class: internet`, so it is not selected. Forwarded `wg0` traffic is not pod-identity
|
||||
traffic at all, and `tun0` exists on **`k3s-prod-3` only** (`10.150.192.3/18`) — the egress-gateway
|
||||
node. A remote client's apparent public address is therefore the **home WAN IP**, which is the
|
||||
intended behaviour and the thing to state when enrolling a device.
|
||||
|
||||
**Not measurable without a connected client.** At the time of writing `wg show wg0` listed the one
|
||||
enrolled peer with **no endpoint and no handshake** on every node, and both the `FORWARD -i wg0` and
|
||||
the `MASQUERADE` counters read **0 packets** — so no client traffic had been forwarded since the
|
||||
power-cycle, and which node the router forwards `udp/51820` to was **undeterminable**. Only the
|
||||
forwarded node shows a peer with an `endpoint` and a recent `latest handshake`.
|
||||
|
||||
## Prerequisites outside this directory
|
||||
|
||||
1. **The `wireguard` kernel module on every node.** Added to `node_baseline_kernel_modules`
|
||||
|
||||
@@ -273,6 +273,84 @@ bytes of WireGuard encapsulation); drop the client to `1280` and re-test.
|
||||
by design. Work inwards: `wg show` on the node holding the forward will show *zero* received bytes
|
||||
if the router is not delivering the packets, and a `handshake` with no completed session if it is.
|
||||
|
||||
## Triage — "the client reaches the LAN and cluster apps, but not the internet"
|
||||
|
||||
Reported 2026-10-17. Work **outwards from the client profile**, because that is where this symptom
|
||||
almost always lives, and because the server side has been measured and is not the cause.
|
||||
|
||||
**1. Read `AllowedIPs` in the client's own `[Peer]` stanza. This one line settles it.**
|
||||
|
||||
| the profile says | meaning |
|
||||
|---|---|
|
||||
| `0.0.0.0/0` | **full tunnel** — the default. Internet *should* be carried. Go to step 2. |
|
||||
| `192.168.2.0/24, 10.90.0.0/24` | **split tunnel** — `--split` was passed, or the profile predates the script. Internet never enters the tunnel **by design**; it uses the device's own uplink, and if that is broken the VPN cannot fix it. Re-render without `--split` to change it. |
|
||||
|
||||
`new-peer.sh` emits a full tunnel **by default** and has since the component's first commit —
|
||||
`--split` is the opt-in. There is no server-side switch for this: **it is a property of the client
|
||||
profile only**, so an already-issued profile keeps whatever it was rendered with until it is
|
||||
re-rendered and re-imported on the device. The two forms differ by one flag:
|
||||
|
||||
```bash
|
||||
./infra/devcontainer/dev.sh run bash -c './infra/vpn-ingress/new-peer.sh <name> <octet>' # full tunnel
|
||||
./infra/devcontainer/dev.sh run bash -c './infra/vpn-ingress/new-peer.sh <name> <octet> --split' # LAN only
|
||||
```
|
||||
|
||||
Re-rendering mints a **new keypair**, so it also needs the new `[Peer]` stanza PR'd into
|
||||
`peers.conf` and the old one deleted. Changing an existing device in place, without new keys, is
|
||||
editing `AllowedIPs` in the profile **on the device** — the server does not care.
|
||||
|
||||
**2. If it is a full tunnel, prove the client traffic is reaching the node at all.** Have the
|
||||
client connected, then watch the two counters that only forwarded traffic moves:
|
||||
|
||||
```bash
|
||||
./infra/devcontainer/dev.sh run bash -c \
|
||||
'kubectl --context k3s-prod -n vpn-ingress exec ds/wireguard -- sh -c "
|
||||
wg show wg0 endpoints; iptables -L FORWARD -n -v | head -5;
|
||||
iptables -t nat -L POSTROUTING -n -v | head -5"'
|
||||
```
|
||||
|
||||
* Only the **forwarded node** shows a peer with an `endpoint`; that is the only way to learn which
|
||||
node the router's `udp/51820` forward points at (the router is unreadable from the cluster).
|
||||
* `FORWARD -i wg0` at **0 packets** on every node means nothing is arriving — the problem is
|
||||
upstream of the cluster (router forward, client, or carrier), not here.
|
||||
* `FORWARD -i wg0` moving while `POSTROUTING … MASQUERADE` stays at **0** is the one server-side
|
||||
failure this symptom could have: un-SNATed `10.90.0.x` packets reach the router and die there,
|
||||
which breaks internet while node-local cluster VIPs still work. It has not been observed.
|
||||
|
||||
**3. Suspect DNS and address family before suspecting routing.** Both fit this symptom exactly:
|
||||
|
||||
* **IPv6.** `AllowedIPs = 0.0.0.0/0` carries **IPv4 only** (see Known limitations). A dual-stack
|
||||
client resolving a public name gets an AAAA, prefers IPv6, and sends it **outside** the tunnel —
|
||||
so LAN and cluster names (IPv4/RFC1918) work while public sites hang. Test by forcing IPv4:
|
||||
`curl -4 https://example.com` from the client. If `-4` works and plain `curl` hangs, this is it,
|
||||
and the fix is on the client (disable IPv6 on the tunnel, or add `::/0` to `AllowedIPs` so it is
|
||||
blackholed rather than leaked — note the tunnel has **no** IPv6 egress, so that blackholes it).
|
||||
* **PiHole.** The profile sets `DNS = 192.168.2.23`. It does resolve public names — verified
|
||||
2026-10-17, `google.com` answered from inside the cluster — but it is also an ad-blocker, so a
|
||||
blocked name is indistinguishable from "no internet" on one site. Test a name you know is not on
|
||||
a blocklist, and compare against `curl https://1.1.1.1/` by **IP**, which needs no DNS at all.
|
||||
|
||||
**4. What is NOT the cause.** Measured 2026-10-17, all three nodes: `ip_forward=1`; the
|
||||
`-s 10.90.0.0/24 ! -o wg0 -j MASQUERADE` rule present, with the preceding `CILIUM_POST_nat` chain
|
||||
**empty** so it cannot short-circuit it; `FORWARD -i/-o wg0` ACCEPT present; the default route
|
||||
`via 192.168.2.1 dev eno1` intact; and the nodes themselves reaching `1.1.1.1`. Also **not** the
|
||||
PIA egress gateway: it selects pods by `egress-class: vpn`, this DaemonSet is labelled
|
||||
`egress-class: internet`, and `tun0` exists on `k3s-prod-3` only — so a full tunnel egresses the
|
||||
**house WAN** and the client's apparent address is the **home WAN IP** (check 4 in step 6).
|
||||
|
||||
## Triage — which L2 announcement lease a node holds does NOT matter
|
||||
|
||||
Do not spend time here. It was investigated at length (PR #69, withdrawn) on the belief that a node
|
||||
could not reach a VIP it announced. Measured 2026-10-17 with **all eight** leases on `k3s-prod-1`:
|
||||
that node reached `192.168.2.20`, `.22`, `.23` and `.24` normally. The lease holder's `ip neigh`
|
||||
for its own VIP does sit at `FAILED` **permanently and harmlessly** — Cilium DNATs LoadBalancer
|
||||
VIPs in BPF on both `eno1` and `wg0` before any neighbour lookup, and the shared Gateway's backend
|
||||
is a node-local socket. Full measurements and the two misleading probes
|
||||
(`ip neigh`, `curl --interface wg0`) are in `platform/vpn-ingress/README.md`.
|
||||
|
||||
`192.168.2.21` (unifi) fails from **all three** nodes, including ones whose ARP resolves. That is a
|
||||
separate, pre-existing fault in that service and has nothing to do with the VPN.
|
||||
|
||||
## Revoking a device
|
||||
|
||||
Delete its `[Peer]` stanza from `peers.conf`, PR, merge. Nothing else — the key stops working on the
|
||||
|
||||
Reference in new issue
Block a user