felhom.eu/documentation/runbooks/offsite-endpoint.md

# RUNBOOK — offsite endpoint provisioning (WG server + PBS + peersync surface)

> **What this creates:** the Felhom offsite endpoint (doc 06 §5) on a blank Debian 13 VM — the
> WG server on **443/UDP**, the offsite PBS with a `/srv` datastore, a drop-everything-else
> firewall, and the hub-driven `felhom-peersync` reconcile surface. Re-running it on a fresh VM
> re-creates the endpoint from nothing (that is the DR story, step 8).
>
> **Validated:** 2026-07-03 on the dev/test endpoint `felhom-hetzner` (Hetzner CX23, Debian 13,
> `167.233.158.164` / `2a01:4f8:1c16:7aa1::1`) with hub v0.32.0. The production endpoint is a
> later re-run of this runbook on a production VM.
>
> Companion piece: the hub side (env + Secret) is `manifests/hub.yaml` + step 6/7 below.
> The peersync script's source of truth is `scripts/felhom-peersync.sh` (v1.0.0).

Parameters used throughout (adjust for a new endpoint):

| Param | Dev value |
|---|---|
| VM | `felhom-hetzner`, `167.233.158.164` (**NOT the live jarrs.eu box** — different server) |
| DNS name | `ep0.felhom.eu` (A + AAAA, **DNS-only / grey-cloud** — proxying breaks WG/UDP + PBS) |
| WG port | **443/udp** (spike P4: handshakes + carries identically to 51820) |
| Tunnel subnet | `10.77.0.0/24`; endpoint in-tunnel IP `10.77.0.1` |
| PBS datastore | `felhom-offsite` at `/srv/pbs-felhom` (**never under `/root`** — the `backup` user cannot traverse it; spike gotcha) |

## 0. Preconditions (operator)

- [ ] The VM is powered on and root-SSH-reachable.
- [ ] DNS `ep0.felhom.eu` → A `167.233.158.164` + AAAA `2a01:4f8:1c16:7aa1::1`, **grey-cloud**.
      Verify: `nslookup ep0.felhom.eu 1.1.1.1` returns the A record. **The AAAA must be the
      box's full `::1` address** — a bare `...:7aa1::` (the subnet zero address) resolves but
      points at nothing (live-run finding). Home-resolver propagation can lag public DNS by
      minutes — a client-side `wg-quick up` that fails to resolve right after record creation
      just needs a retry.
- [ ] Sanity: `ssh root@167.233.158.164 hostname` → `felhom-hetzner` (the throwaway CX23), not
      any production box.

## 1. Base (on the box, as root)

```sh
apt update && DEBIAN_FRONTEND=noninteractive apt full-upgrade -y
printf 'PasswordAuthentication no\n' > /etc/ssh/sshd_config.d/90-felhom.conf && systemctl reload ssh
sshd -T | grep -i '^passwordauthentication'   # must print: passwordauthentication no
```
(The explicit drop-in beats auditing defaults — Hetzner images have no explicit line at all.)

## 2. WG server

```sh
apt install -y wireguard-tools          # module ships in the stock Debian 13 kernel
umask 077
wg genkey > /etc/wireguard/wg0.key      # server private key — NEVER displayed/copied anywhere
wg pubkey < /etc/wireguard/wg0.key      # RECORD this pubkey → hub registration (step 7)
cat > /etc/wireguard/wg0.conf.head <<EOF
[Interface]
Address = 10.77.0.1/24
ListenPort = 443
MTU = 1420
PrivateKey = $(cat /etc/wireguard/wg0.key)
EOF
chmod 600 /etc/wireguard/wg0.conf.head
cp -p /etc/wireguard/wg0.conf.head /etc/wireguard/wg0.conf   # zero peers initially
systemctl enable --now wg-quick@wg0
wg show wg0
```
Verify: `wg show wg0` → `listening port: 443`, no peers. **No `SaveConfig`** anywhere — the
peersync script owns persistence (head-file + generated peers; `wg-quick save` would rewrite
the conf nondeterministically).

> **NEVER run `wg show <if> dump` in a logged/shared session** — field 1 of its interface line
> is the **private key**. Plain `wg show` prints only the public key. (Live-run lesson: a
> `dump | cut` leaked the first server key into a session log → the key was rotated on the
> spot. If it happens to you: regenerate the keypair, rebuild `wg0.conf.head` + `wg0.conf`,
> restart `wg-quick@wg0`, re-`PUT` the new pubkey to the hub — 2 minutes, zero peer downtime
> beyond the restart.)

## 3. Firewall (nftables, v4+v6)

```sh
cat > /etc/nftables.conf <<'EOF'
#!/usr/sbin/nft -f
flush ruleset
table inet filter {
    chain input {
        type filter hook input priority 0; policy drop;
        ct state established,related accept
        iif "lo" accept
        tcp dport 22 accept
        udp dport 443 accept
        tcp dport 8007 iifname "wg0" accept
        ip protocol icmp accept
        meta l4proto ipv6-icmp accept
    }
    chain forward {
        type filter hook forward priority 0; policy drop;
    }
}
EOF
systemctl enable --now nftables
nft list ruleset | head -20
sysctl net.ipv4.ip_forward
```
Verify (doc 06 §4.5 — no inter-peer routing by topology): forward chain policy **drop**,
`net.ipv4.ip_forward = 0`. From an outside vantage: `ssh` (22) connects; **8007 publicly
CLOSED** — `curl -sk --max-time 8 https://<public-ip>:8007/` must time out (the spike-P2b
firewall proof, repeated). 443/udp is proven by the first WG handshake in step 7's validation.

## 4. PBS

```sh
curl -fsSL https://enterprise.proxmox.com/debian/proxmox-release-trixie.gpg \
  -o /usr/share/keyrings/proxmox-archive-keyring.gpg
echo 'deb [signed-by=/usr/share/keyrings/proxmox-archive-keyring.gpg] http://download.proxmox.com/debian/pbs trixie pbs-no-subscription' \
  > /etc/apt/sources.list.d/pbs.list
apt update && DEBIAN_FRONTEND=noninteractive apt install -y --no-install-recommends \
  proxmox-backup-server proxmox-backup-client   # client is a SEPARATE package (namespace ops need it)
rm -f /etc/apt/sources.list.d/pbs-enterprise.sources   # the install adds the ENTERPRISE repo → 401s every apt update
apt update
proxmox-backup-manager datastore create felhom-offsite /srv/pbs-felhom
# prove namespace ops (per-customer tenancy, doc 06 D5) with a THROWAWAY token, then remove it
# (root@pam has no password on a cloud image; S4 wires the real per-customer tokens):
umask 077
proxmox-backup-manager user generate-token root@pam nsproof > /root/.nsproof
proxmox-backup-manager acl update /datastore/felhom-offsite DatastoreAdmin --auth-id 'root@pam!nsproof'
export PBS_PASSWORD="$(tr -d '\n' < /root/.nsproof | sed -n 's/.*"value": "\([^"]*\)".*/\1/p')"
export PBS_FINGERPRINT="$(proxmox-backup-manager cert info | grep -i fingerprint | awk '{print $3}')"
proxmox-backup-client namespace create test-ns --repository 'root@pam!nsproof@localhost:felhom-offsite'
proxmox-backup-client namespace delete test-ns --repository 'root@pam!nsproof@localhost:felhom-offsite'
proxmox-backup-manager user delete-token root@pam nsproof && rm -f /root/.nsproof
```
Verify: `systemctl is-active proxmox-backup proxmox-backup-proxy` → both `active`; the
datastore parent is `/srv` (world-traversable — a datastore under `/root` fails with
`Permission denied` for the `backup` user). GUI: reachable ONLY via SSH port-forward
(`ssh -L 8007:127.0.0.1:8007 root@<box>`) or through the tunnel — by design, no public 8007.

## 5. Peersync surface

```sh
useradd -m -s /bin/sh felhom-peersync   # real shell required for the forced command;
                                        # access is bounded by the key options + sudoers, not the shell
apt install -y jq
# install the script (from the repo; strip CRLF if staging via a Windows checkout):
tr -d '\r' < scripts/felhom-peersync.sh > /usr/local/bin/felhom-peersync
chown root:root /usr/local/bin/felhom-peersync && chmod 0755 /usr/local/bin/felhom-peersync
cat > /etc/sudoers.d/felhom-peersync <<'EOF'
felhom-peersync ALL=(root) NOPASSWD: /usr/local/bin/felhom-peersync
EOF
visudo -c
```
Verify: `visudo -c` → "parsed OK". The authorized_keys entry is written in step 6 (it needs
the hub's pubkey):

```
restrict,command="sudo /usr/local/bin/felhom-peersync" ssh-ed25519 AAAA... hub@felhom
```

(`restrict` kills pty/forwarding/X11/agent in one word; the forced command overrides whatever
the client asks to run.)

## 6. Hub credential (build server + the box + k3s)

On the build server (192.168.0.180):

```sh
ssh-keygen -t ed25519 -f wg-endpoint-ssh -N "" -C hub@felhom
```

- The **pubkey** (`wg-endpoint-ssh.pub`) goes into step 5's authorized_keys line on the box:
  `printf 'restrict,command="sudo /usr/local/bin/felhom-peersync" %s\n' "$(cat wg-endpoint-ssh.pub)" > /home/felhom-peersync/.ssh/authorized_keys`
  (as root on the box; `.ssh` dir 0700, file 0600, owner `felhom-peersync`).
- Read the endpoint's **host key on the box itself** (never trust `ssh-keyscan` alone):
  `cat /etc/ssh/ssh_host_ed25519_key.pub`
- Create the k8s Secret, then **shred the local private key** — from this point it exists ONLY
  in the Secret:

```sh
sudo kubectl -n felhom-system create secret generic wg-endpoint-ssh \
  --from-file=key=wg-endpoint-ssh \
  --from-literal=hostkey='ssh-ed25519 AAAA...the-host-key-line'
shred -u wg-endpoint-ssh wg-endpoint-ssh.pub
```

Then apply the manifest + roll the hub (`manifests/hub.yaml` already mounts the Secret as
optional): expect `[INFO] WG peer-sync enabled (endpoint 167.233.158.164:22, ...)` in the hub
log (before the Secret existed it says `disabled (endpoint not configured)`).

## 7. Register the endpoint in the hub

```sh
curl -s -X PUT https://hub.felhom.eu/api/v1/admin/wg/endpoint \
  -H "Authorization: Bearer <GLOBAL-KEY out-of-band>" \
  -d '{"dns_name":"ep0.felhom.eu","wg_port":443,"server_pubkey":"<step-2 pubkey>",
       "tunnel_subnet":"10.77.0.0/24","pbs_tunnel_ip":"10.77.0.1"}'
```

Validation loop (the S1 done-criterion): `POST /api/v1/admin/wg/peers {"pubkey":...}` with a
throwaway pubkey → response `sync:"ok"` → on the box `wg show wg0 peers` lists it →
`DELETE /api/v1/admin/wg/peers {"pubkey":...}` → gone from `wg show`. A live handshake +
`curl -sk https://10.77.0.1:8007/` through a throwaway client tunnel proves 443/udp + the
wg0-only 8007 rule end-to-end.

## 8. Re-provision from nothing (the DR story)

The rebuild is **steps 1–7 on a fresh VM**. What is lost vs regenerable:

- **WG server keypair — regenerable**, but every existing peer's config then points at a dead
  server pubkey. Until S2/S3 deliver endpoint coords via desired-state, re-keying is a
  **manual client-side update** (dev-acceptable; note per doc 06 §7). Register the new pubkey
  via step 7; peers re-converge as they're updated.
- **The hub's peer registry survives** (it lives in the hub DB): a rebuilt endpoint converges
  on the first reconciler tick (≤5 min) or the next mutation — no re-registration needed.
- **The PBS datastore is the real loss** — customer ciphertext. PBS-side redundancy is a
  deferred economics call (doc 06 §7); until then, endpoint loss = offsite history loss
  (customers still hold local backups + a re-seedable offsite).
- The hub's SSH credential + pinned host key must be **rotated on rebuild** (new box = new
  host key): repeat step 6 (`kubectl delete secret wg-endpoint-ssh` first), roll the hub.