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# OPNsense DNS Architecture

**Last updated:** 2026-05-28
**Status:** Active

## Overview

Two DNS services run on OPNsense:

- **Unbound** — primary resolver on port 53, handles all external DNS with DNSSEC, DoT upstreams
- **dnsmasq** — local DHCP and host resolution on port 5353, handles `kaburu.lan` records

Unbound forwards `kaburu.lan` queries to dnsmasq on 127.0.0.1:5353, so all devices get a single DNS server (OPNsense at 192.168.0.1) for both local and external resolution.

## Unbound Configuration

| Setting | Value |
|---|---|
| Port | 53 |
| Interface | All (listens on all, outgoing locked to Mullvad) |
| DNSSEC | Enabled |
| Outgoing interface | Mullvad_VPN (opt5) |
| regdhcp | Enabled |
| regdhcpstatic | Enabled |
| regdhcpdomain | kaburu.lan |

### Upstream Resolvers (DoT) — Active

| UUID | Name | Server | Port | Verify |
|---|---|---|---|---|
| 48000e06 | Mullvad DNS TLS 1 | 193.138.218.74 | 853 | adblock.dns.mullvad.net |
| 09060f42 | Mullvad DNS TLS 2 | 194.242.2.2 | 853 | adblock.dns.mullvad.net |

### Upstream Resolvers — Disabled

| UUID | Name | Server | Reason |
|---|---|---|---|
| d53fa713 | Cloudflare DoT | 1.1.1.1 | DNS leak — Cloudflare IPs appeared on mullvad.net/check |
| 8da39e2d | Quad9 DoT | 9.9.9.9 | DNS leak |
| 76093144 | Cloudflare Forward | 1.1.1.1 | DNS leak |
| 08dd7e77 | Quad9 Forward | 9.9.9.9 | DNS leak |

### Query Forwarding

| Domain | Server | Port |
|---|---|---|
| kaburu.lan | 127.0.0.1 | 5353 |

## dnsmasq Configuration

| Setting | Value |
|---|---|
| DNS port | 5353 (not on port 53) |
| Interface | LAN |
| Domain | kaburu.lan |
| regdhcp | Enabled |
| regdhcpstatic | Enabled |
| DNSSEC | Disabled (Unbound handles this) |
| no_resolv | Enabled (does not use upstream resolvers) |

## Local Domain

All local hosts resolve under `kaburu.lan` — e.g. `kaburuaibox.kaburu.lan`

Host records are managed in dnsmasq under Services → Dnsmasq DNS → Hosts.

## Key Host Records

| Hostname | IP | Description |
|---|---|---|
| kaburuaibox | 192.168.0.253 | HP Z840 AI Server |
| TrueNAS | 192.168.0.251 | TrueNAS MicroServer Gen8 |
| TrueNAS-1gb-1 | 192.168.0.200 | TrueNAS port 1 |
| TrueNAS-1gb-2 | 192.168.0.201 | TrueNAS port 2 |
| KABURU-UM790-MAIN | 192.168.0.143 | UM790 Pro mini PC |
| KaburuLINK | 192.168.0.250 | Unraid box |
| homeassistant | 192.168.0.123 | Home Assistant |
| ILOCZ162000TP | 192.168.0.155 | HP Z840 iLO4 port |
| keeplink-sw | 192.168.0.10 | KeepLink KP-9000 switch |
| eap653-01 | 192.168.0.101 | TP-Link EAP653 AP1 |
| eap653-02 | 192.168.0.100 | TP-Link EAP653 AP2 |
| eap110-outdoor | 192.168.0.102 | TP-Link EAP110 Outdoor AP |

## VLANs

| VLAN | Interface | DHCP Range | Domain |
|---|---|---|---|
| LAN | lan | 192.168.0.51–250 | kaburu.lan |
| CamerasVLAN | opt7 | 192.168.20.10–100 | kaburu.lan |
| IOTVlan | opt8 | 192.168.30.10–100 | kaburu.lan |

## Change Log

### 2026-05-28 — DNS Leak Fix

**Problem:** mullvad.net/check showed DNS requests leaking via Cloudflare (172.70.88.163, 172.70.88.164 and IPv6 equivalents) despite VPN being active.

**Root cause:** Cloudflare and Quad9 DoT/Forward entries were enabled in Unbound. Even with outgoing_interface set to Mullvad (opt5), these upstream resolvers were resolving outside the VPN tunnel and their IPs appeared in DNS leak tests.

**Fix:**
- Disabled all 4 Cloudflare/Quad9 DoT and Forward entries in Unbound
- Enabled both Mullvad DoT entries (193.138.218.74 and 194.242.2.2, both verify adblock.dns.mullvad.net)
- Config edited directly via SSH: `perl -i -0pe` on `/conf/config.xml`
- Unbound reconfigured via API
- Pre-change backup saved to `/conf/config.xml.bak-20260528-prednsfix` on OPNsense

### 2026-05-17 — DNS Architecture Refactor

- Unbound bound to LAN interface only (was listening on all interfaces)
- regdhcp and regdhcpstatic enabled on Unbound
- dnsmasq moved from port 53 to port 5353
- Unbound query forward added for kaburu.lan → 127.0.0.1:5353
- This resolves the issue where dnsmasq host records were not visible to Unbound

### 2026-05-28 — DoH Browser Leak Fix

**Problem:** After fixing Unbound upstreams, mullvad.net/check still showed Cloudflare IPs (172.69.193.x) leaking. These are Cloudflare's **DNS-over-HTTPS resolver IPs**, not plain DNS. The browser (Brave) was bypassing OPNsense entirely and sending DoH queries directly to Cloudflare port 443 over the VPN.

**Root cause:** Brave and other modern browsers have built-in encrypted DNS (DoH) configured to Cloudflare/Google by default. This traffic goes to port 443 so it's indistinguishable from HTTPS — it bypasses any DNS server the OS/router sets.

**Fix — two firewall rules added to LAN (top of ruleset, quick):**

| UUID | Rule | Interface | Proto | Destination | Port | Action |
|---|---|---|---|---|---|---|
| b1000001 | Block DoH providers | LAN | tcp/udp | DoH_Block alias | 443 | block |
| b1000002 | Block rogue plain DNS | LAN | tcp/udp | !192.168.0.1 | 53 | block |

**DoH_Block alias (uuid: a1b2c3d4-0000-0000-0000-doh000000001):**
- 1.1.1.1, 1.0.0.1 (Cloudflare)
- 8.8.8.8, 8.8.4.4 (Google)
- 9.9.9.9, 149.112.112.112 (Quad9)
- 208.67.222.222, 208.67.220.220 (OpenDNS)
- 94.140.14.14, 94.140.15.15 (AdGuard)

**Result:** All three green on mullvad.net/check — Using Mullvad VPN / No DNS leaks / No WebRTC leaks. Confirmed 2026-05-28.

**Also:** Brave "Use secure DNS" setting disabled in browser settings (Settings → Privacy → Security → Use secure DNS → off). Belt and braces — the firewall block rules handle any device that has it on, but disabling in-browser is cleaner where possible.

**Note:** The plain-DNS redirect rule (rule b1000002) also prevents any device from using a hardcoded DNS server (e.g. 8.8.8.8 in network settings).