oikos/containers/107-dns.md

# 107 — `dns`

Homelab DNS server (Technitium). Replaces the dnsmasq that lived on [124 — authentik](124-authentik.md); single-purpose, one job.

## At a glance
- **Hostname:** `dns`
- **IP:** `192.168.8.2` (static — stable, decoupled from any app)
- **Privilege:** privileged (Docker-in-LXC, `features: nesting=1`)
- **Resources:** 1 core / 1 GiB / 8 GiB rootfs
- **Created:** 2026-06-01, Debian 13. Its own resolver is `1.1.1.1` (no circular dependency on the DNS it serves).

## Role
Authoritative split-horizon DNS for `hubris.network` on the LAN/mesh, plus recursive forwarding (`1.1.1.1`, `8.8.8.8`) for everything else. Technitium runs in Docker (`technitium/dns-server:latest`, `network_mode: host`), web console on `:5380`.

## The `hubris.network` zone
- Specific A overrides: app names → `192.168.8.175` (Caddy), `nfs-export → 192.168.8.200`, `auth/sso/...` as needed.
- `auth.hubris.network → 82.165.190.79` (VPS Authentik), `sso.hubris.network → 192.168.8.175` (LAN forward-auth outpost).
- **Wildcard** `*.hubris.network → 82.165.190.79` — mirrors the public IONOS wildcard so undefined names (e.g. `netbird`) resolve to the VPS, matching public behaviour.
- **MX / SPF-TXT / CAA replicated from public** so an authoritative zone doesn't shadow `hubris.network` email/cert records.

## Config / access
- `/opt/technitium/docker-compose.yml`; admin password in `/opt/technitium/admin_password.txt` (mode 600 — sops-encrypt in Phase 5).
- Console: `http://192.168.8.2:5380` (user `admin`).
- API: `http://192.168.8.2:5380/api/...` (token via `/api/user/login`). Zone was built via the API.

## Who points here
- **NetBird mesh peers:** resolve via the **NetBird managed DNS zone**, kept in sync *from* this Technitium (see dns-sync below). The `home-lab-dns` nameserver group (`→ 192.168.8.2`) is a thin fallback forwarder.
- **Homelab DHCP clients:** Technitium's own DHCP scope hands out `192.168.8.2` as the DNS server for `192.168.8.x` leases (see DHCP section below).
- **Plain LAN clients (`192.168.178.x`):** Fritz!Box DHCP still hands out Fritz!Box itself (`192.168.178.1`) as DNS — no split-horizon for non-mesh clients. Changing this requires a secondary DNS fallback, which Fritz!OS 8.x doesn't expose in a single DHCP field.

## dns-sync (Technitium = authoring source)
`/opt/dns-sync/sync.py` (cron `*/10`, logs `/var/log/dns-sync.log`) reconciles this zone's named A-records → the NetBird managed DNS zone via the NetBird API (`/api/dns/zones/{id}/records`). Token at `/opt/dns-sync/netbird-token` (mode 600; source of truth in sops `secrets/netbird-pat.yaml`). **Edit DNS only here**; the sync propagates to the mesh. It deletes NetBird records absent from Technitium. Tracked: [scripts/dns-sync.py](../scripts/dns-sync.py). *Why this exists:* NetBird won't forward to Technitium for mesh peers (self-IP / nameserver-group quirks), so we sync into the managed zone instead — see [dns.md](../infrastructure/dns.md).

## DHCP

Technitium also runs a DHCP server for the homelab subnet (enabled 2026-06-02):
- **Scope:** `homelab` — `192.168.8.241 – 192.168.8.254`
- **Gateway:** `192.168.8.1` (Proxmox `vmbr0` alias)
- **DNS:** `192.168.8.2` (self)
- **Lease time:** 24 h

Replaces the DHCP that was previously served by the Slate AX router. Static-IP LXCs (`.101–.239`) are excluded from the pool. Pool narrowed from `.100–.240` to `.241–.254` on 2026-06-03 to eliminate IP conflict risk.

## Related
- [124 — authentik](124-authentik.md) — retired host of the old dnsmasq
- [DNS split-horizon](../infrastructure/dns.md)
- [Mesh](../infrastructure/mesh.md)

## Changelog

### 2026-06-24 — A record `trmnl.hubris.network → 192.168.8.175`
Added for [trmnl (128)](128-trmnl.md) (LAN path via [Caddy (121)](121-caddy.md)); propagated to the NetBird managed zone by `dns-sync`.

### 2026-06-06 — dns-sync cron installed (had been missing since deployment)
Although the 2026-06-03 changelog claimed "cron */10", **no crontab was actually configured** on the LXC. The sync was running only via ad-hoc manual invocations during incident debugging. Fixed by adding `/etc/cron.d/dns-sync`.

### 2026-06-03 — DHCP pool narrowed to `.241–.254`
Previous pool `.100–.240` overlapped with all static LXCs/VMs (`.101–.239`). Shrunk via API (`/api/dhcp/scopes/set`). 11 stale DHCP leases in `.101–.110` remain until natural expiry (2026-06-04). See [plan](../plans/2026-06-03-dhcp-pool-exclude-static-ips.md).

### 2026-06-03 — dns-sync added (Technitium → NetBird managed zone)
This Technitium became the single DNS authoring source; `/opt/dns-sync/sync.py` (cron */10) reconciles named A-records into the NetBird managed zone via the API. Fixed previously-broken mesh names (`sso`, `nfs-export`, `mcp`, `secrets`) by adding them to the managed zone; reaped obsolete `files`/`photos-new`. See [dns.md](../infrastructure/dns.md).

### 2026-06-02 — DHCP server enabled; replaces Slate AX DHCP
Enabled Technitium's built-in DHCP server for `192.168.8.0/24` (scope `homelab`, range `.100–.240`, gateway `192.168.8.1`, DNS self). Previously the Slate AX sub-router served DHCP for the homelab subnet. With the Slate AX retired and Proxmox now the subnet router, Technitium takes over DHCP. Configured via the Technitium API (`/api/dhcp/scopes/set`). DHCP LXCs kept their Slate AX leases until expiry, then renewed from Technitium.

### 2026-06-01 — created; replaced dnsmasq on 124
Stood up Technitium at `192.168.8.2`, imported the split-horizon zone (specific A + wildcard + MX/SPF/CAA), made it the primary nameserver in the NetBird `home-lab-dns` group. Verified all names resolve with dnsmasq/124 stopped; [LXC 124 retired](124-authentik.md).