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wiki-vault/Sources/Homelab/2026-05-25-wireguard-postgres-access-initial-deploy.md

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created path project tags type
2026-05-25 Sources/Homelab wireguard-postgres-access
wireguard
postgres
networking
knot
dns
homelab
session-notes

Outcome

Stood up WireGuard hub-and-spoke overlay on herbys-dev (wg-lan interface, 10.99.0.0/24). First peer (ThinkPad as POC, standing in for tower) handshakes and pings hub successfully. Knot DNS serves db.wg.herbylab.dev and herbys-dev.wg.herbylab.dev → 10.99.0.1. Postgres rebind handled by Lovebug out of band.

What got built

  • Hub on herbys-dev: wg-lan interface at 10.99.0.1/24, listening UDP/51820, enabled via wg-quick@wg-lan systemd unit
  • First peer (ThinkPad): 10.99.0.2, dials hub via 10.0.21.207:51820, persistent keepalive 25s
  • OpenWrt firewall: Lab→Private UDP/51820 allowed (scoped to source IP)
  • Knot zone update: herbylab.dev zone gained a $ORIGIN wg.herbylab.dev. section with two A records, serial bumped
  • Per-host key generation pattern: private keys generated and locked to each host; only public keys cross machines

Learnings

  • $(cat secret_file) splice pattern for moving on-disk secrets into config files without crossing the terminal. Keeps secrets out of scrollback and shell history.
  • read -s (bash) / read -s -P (fish) for prompting secrets without echo when the secret is coming from a human, not a file.
  • WireGuard AllowedIPs is both a routing rule and an ACL — on the hub it's per-peer (/32 per peer); on the client it's "what to route through the tunnel" (/24 for the whole overlay subnet).
  • PersistentKeepalive is needed when the peer is behind NAT or stateful firewalls (inter-VLAN through OpenWrt counts). Without it, the return path can age out.
  • DNS zone files — three ways to handle subdomains:
    1. Flat records in parent zone (db.wg IN A ...) — simplest, fine for small zones
    2. $ORIGIN shift mid-file — visual grouping, same zone
    3. Separate zone file with NS delegation — real separation, production pattern Chose Way 2 here. Way 3 is overkill until there's a real reason to split.
  • Serial number must increment on every zone change — and the file edit doesn't take effect until knotc zone-reload. knotc zone-status shows the loaded serial, not the file's serial.
  • DNS caching layers to consider when fixes don't propagate: Pi-hole, local stub resolver (systemd-resolved if present), application caches. TTL bounds the worst case.

Decisions

  • Way 2 (origin shift) chosen over separate zone for wg.herbylab.dev. Two records doesn't justify a new zone file.
  • POC on laptop, not tower — proved the shape works before touching the actual target rig. Tower peer to be added later as a follow-up.
  • Knot record naming: db.wg.herbylab.dev (service-oriented) and herbys-dev.wg.herbylab.dev (host-oriented), both pointing at 10.99.0.1. Use whichever fits the connection string.

How to add a new peer to wg-lan

1. Generate keypair on the new peer

sudo mkdir -p /etc/wireguard
cd /etc/wireguard
sudo sh -c 'umask 077; wg genkey | tee <peer>_private.key | wg pubkey > <peer>_public.key'
sudo cat /etc/wireguard/<peer>_public.key

Capture the public key output. Replace <peer> with a short identifier (e.g., tower, nas).

2. Register the peer's pubkey on the hub (herbys-dev)

Append to /etc/wireguard/wg-lan.conf:

[Peer]
# <peer-name>
PublicKey = <peer-public-key>
AllowedIPs = 10.99.0.<N>/32

Where <N> is the next free address (.2 taken, start at .3 for new peers).

Reload the hub without dropping existing tunnels:

sudo wg syncconf wg-lan <(sudo wg-quick strip wg-lan)

(wg syncconf applies the new config without bouncing the interface — existing peers stay connected.)

3. Write the peer's config

On the new peer:

sudo sh -c 'cat > /etc/wireguard/wg-lan.conf << EOF
[Interface]
PrivateKey = $(cat /etc/wireguard/<peer>_private.key)
Address = 10.99.0.<N>/24

[Peer]
# herbys-dev hub
PublicKey = nbLpIXOmbaIXeJySVLZ+8sCQkR9Qz2uQzAfcIkTACmE=
Endpoint = 10.0.21.207:51820
AllowedIPs = 10.99.0.0/24
PersistentKeepalive = 25
EOF'
sudo chmod 600 /etc/wireguard/wg-lan.conf

4. OpenWrt firewall (if peer is on a new VLAN)

If the new peer is on a VLAN that doesn't already have a Lab→Private:UDP/51820 rule, add one in LuCI. Scope source to the peer's IP if possible.

5. Bring tunnel up and verify

sudo systemctl enable --now wg-quick@wg-lan
sudo wg show
ping -c 3 10.99.0.1

wg show should list the hub peer with a recent handshake and non-zero transfer after the ping.

Open follow-ups

  • Add actual tower (not laptop) as a peer
  • Confirm Postgres boot ordering — wg-lan must be up before Docker brings Postgres up (add After=wg-quick@wg-lan.service to Docker unit, or similar)
  • Document key rotation procedure (what to do if a peer private key leaks)
  • Sort out laptop's DNS resolver — systemd-resolved not present, need to know what's actually resolving for deliberate cache flushes
  • Ansible role: extend in-progress role to template hub config from peer registry once the manual pattern is stable

References

  • Project plan: wireguard-postgres-access
  • Knot zone: /var/lib/knot/herbylab.dev.zone
  • Hub config: /etc/wireguard/wg-lan.conf on herbys-dev (10.0.21.207)