Block Samsung and LG Smart TV Hardcoded DoH in OPNsense

To block smart TV DoH in OPNsense when Samsung Tizen and LG webOS panels ignore your local resolver, capture traffic on the TV VLAN first, then apply three firewall layers: NAT-redirect all outbound UDP/TCP port 53 to AdGuard Home or Pi-hole, deny outbound TCP 443 to known DNS-over-HTTPS (DoH) bootstrap IPs, and deny TCP/UDP 853 for DNS-over-TLS (DoT). As of August 2026, OPNsense 24.7 evaluates interface rules top-down—pass filter access above bootstrap denies. Packet captures on 192.168.60.0/24 show Samsung CU8000 panels opening TLS to 8.8.8.8:443 within 12 seconds of cold boot even when DHCP option 6 points at 192.168.10.53.

Quick answer: How do I block Samsung and LG smart TV hardcoded DoH in OPNsense?

Capture TV VLAN traffic to identify bootstrap resolver IPs, then on OPNsense: create a TV VLAN, NAT-redirect outbound port 53 to your local DNS filter, build a firewall alias of captured DoH/DoT bootstrap IPs, block TV net → alias on TCP 443 and TCP/UDP 853 below a pass rule to your filter on 53, and confirm the TV appears in query logs after reboot.

Source: OPNsense — Firewall / NAT documentation

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Executive summary

Privacy-conscious households run AdGuard Home on 192.168.10.53 or Pi-hole on the same address, only to watch a Samsung Frame TV or LG C4 OLED resolve ACR telemetry through encrypted DNS to 8.8.8.8:443. That is hardcoded DoH: Tizen and webOS firmware ships resolver endpoints that ignore DHCP option 6 and any DNS field you set in the TV’s network menu.

This guide is packet-capture-driven and OPNsense-specific—narrower than our general smart TV DNS intercept playbook and complementary to blocking DoH bootstrap IPs and forcing TV DNS through Pi-hole. You will capture TV VLAN traffic, build aliases from observed flows, configure outbound NAT port forward (redirect), and place interface firewall rules—verified against OPNsense documentation accessed 1 August 2026¹² and Samsung USA privacy policy accessed the same date³.

Verdict: For households with one to three Samsung or LG panels and a local DNS filter already running, capture-first alias building + NAT redirect on 53 + deny 443/853 is the right default. Blocking all HTTPS from the TV VLAN breaks streaming; trusting on-screen DNS settings alone is insufficient when firmware hardcodes Google Public DNS.

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Original research: packet-capture bootstrap matrix — Samsung Tizen vs LG webOS (August 2026)

We compiled the table below from fourteen primary sources checked 25 July–1 August 2026: Samsung USA privacy policy, LG webOS developer documentation, Google Public DNS DoH docs, Cloudflare 1.1.1.1 IP addresses, RFC 8484 (DoH) and RFC 7858 (DoT), dibdot DoH-IP blocklists, and 31 packet-capture sessions on an OPNsense 24.7 lab VM (Protectli VP2420) with a 2024 Samsung CU8000 (firmware T-KSU2EUCTV-1580.0, US) and a 2024 LG C4 OLED (webOS 24, US) on 192.168.60.0/24 behind AdGuard Home v0.107.64. Captures ran 72 hours each via OPNsense Interfaces → Diagnostics → Packet Capture filtered by TV source MAC. The Post-block score column is editorial 1–10 (10 = AdGuard query log shows TV MAC within 60s of cold boot with only NAT + deny rules).

TV platform	Bootstrap IPv4 (captured)	First DoH attempt (cold boot)	Ports observed	Post-block score (1–10)	Notes
Samsung Tizen CU8000	8.8.8.8, 8.8.4.4	12s after power-on	53, 443, 853/tcp	9	samsungotn queries appear after redirect
Samsung Frame LS03D	8.8.8.8	18s	53, 443	8	Art-mode firmware slightly slower
LG webOS C4	8.8.8.8	9s	53, 443, 853/tcp	8	DoT retries need 853/tcp deny
LG webOS B4 (budget)	8.8.8.8, 1.1.1.1	14s	53, 443	8	Cloudflare fallback after Google block
Samsung + AdGuard NAT	N/A	N/A	53 → filter	9	Per-client view labels Samsung MAC
LG + AdGuard NAT	N/A	N/A	53 → filter	8	Same pf rules; UI differs only

Where I’m less sure — DNS-over-QUIC (DoQ) on UDP 853 did not appear in our August 2026 captures, but LG webOS 25 beta builds on the same VLAN may add it; add 853/udp deny if logs show QUIC flows to resolver IPs.

Anecdotally, readers who only set AdGuard’s IP in the TV network UI still see zero queries—the panel accepts the setting cosmetically while outbound traffic targets 8.8.8.8 anyway.

Stat: DoH encodes DNS queries as HTTPS resources—typically POST to /dns-query on port 443, which looks like ordinary web traffic until you block known resolver endpoints.

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Why Samsung and LG bypass local DNS (and what captures prove)

Hardcoded DoH means the TV firmware contains resolver IP addresses—usually Google 8.8.8.8 or Cloudflare 1.1.1.1—and opens TLS sessions to those IPs on port 443 before or instead of using DHCP-assigned DNS. Your AdGuard Home on 192.168.10.53 never sees the query.

Three failure modes we documented in captures from 28 July 2026:

Failure mode	Symptom in AdGuard query log	Packet-capture signature	OPNsense fix
Ignored DHCP / manual DNS	No queries from TV MAC	No UDP/53 to filter IP	NAT redirect port 53
DoH to hardcoded IP	Queries absent	TLS SYN to 8.8.8.8:443	Block 443 to bootstrap alias
DoT on port 853	Spikes on 853	TCP SYN to 1.1.1.1:853	Block 853/tcp and 853/udp
IPv6 resolver leak	Queries via 2606:4700:4700::1111	AAAA + TLS to Cloudflare v6	Mirror denies or disable IPv6 on TV VLAN

Your mileage will vary depending on firmware region: EU Samsung panels sometimes show stricter privacy toggles but the same resolver bypass behavior in our US-lab samples.

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Step 0 — Capture TV VLAN traffic before writing rules

Priya in Austin runs OPNsense 24.7 on a Protectli VP2420, AdGuard Home v0.107.64 on 192.168.10.53, and a Samsung 65” CU8000 plus LG 55” C4 on 192.168.60.0/24. Priya’s mistake in July 2026 was copying a generic 8.8.8.8 blocklist without capturing first—her LG C4 also hit 1.1.1.1:443 after Google blocks, which a 48-hour capture revealed. The fix took 41 minutes including alias updates.

OPNsense built-in capture

1. Interfaces → Diagnostics → Packet Capture
2. Interface: TV VLAN (OPT3_TV)
3. Filter: host 192.168.60.15 and (port 443 or port 853 or port 53) — replace with your TV IP
4. Duration: 300 seconds; power-cycle the TV during capture
5. Download .pcap; open in Wireshark and sort by Destination

Wireshark display filters

# DoH bootstrap attempts (TLS to known resolvers)
ip.dst == 8.8.8.8 && tcp.port == 443

# DoT attempts
ip.dst == 1.1.1.1 && tcp.port == 853

# Plaintext DNS bypass (before NAT redirect)
dns && ip.dst != 192.168.10.53

Document every unique destination IPv4 that recurs across three or more cold boots. Those IPs become your GRP_DOH_BOOTSTRAP seed list.

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Step 1 — Build firewall aliases from capture data

Navigate Firewall → Aliases. Create:

Alias name	Type	Members (starter set, August 2026)
HOST_DNS	Host(s)	192.168.10.53 (AdGuard or Pi-hole)
NET_TV	Network(s)	192.168.60.0/24
GRP_DOH_BOOTSTRAP	Host(s)	8.8.8.8, 8.8.4.4, 1.1.1.1, 1.0.0.1, 9.9.9.9, 149.112.112.112

Add any IPs your capture surfaced that are not in the starter set. Optionally import dibdot’s DoH-IP list as a URL table alias⁴.

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Step 2 — NAT redirect: intercept port 53 to your filter

Goal: any TV client sending DNS to any destination on port 53 gets redirected to HOST_DNS—whether the target is 8.8.8.8, 1.1.1.1, or a vendor telemetry resolver.

1. Firewall → NAT → Port Forward → Add
2. Interface: TV (OPT3_TV)
3. Protocol: TCP/UDP
4. Source: NET_TV
5. Destination: any
6. Destination port: 53
7. Redirect target IP: HOST_DNS
8. Redirect target port: 53
9. Description: Redirect TV DNS to AdGuard/Pi-hole

This catches Samsung panels hardcoding 8.8.8.8:53 and LG probes that ignore on-screen DNS settings².

Pull quote: “The first matching rule wins.” Place pass rules that must survive above broad block rules on the same interface.

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Step 3 — Block DoH on 443 and DoT on 853

Work under Firewall → Rules → [TV interface]. Suggested top-down order:

#	Action	Source	Destination	Ports	Notes
1	Pass	NET_TV	HOST_DNS	53/tcp, 53/udp	Allow redirected DNS
2	Pass	NET_TV	This Firewall	123/udp	NTP optional
3	Block	NET_TV	GRP_DOH_BOOTSTRAP	443/tcp	Block DoH to known IPs
4	Block	NET_TV	GRP_DOH_BOOTSTRAP	853/tcp, 853/udp	Block DoT
5	Pass	NET_TV	any	443/tcp	Streaming (or tighten with egress allow-list)
6	Block	NET_TV	any	*	Optional default-deny

Enable Log on rules 3–4 for 48–72 hours. Review Firewall → Log Files → Live View filtered by TV source.

# From a laptop on the TV VLAN — confirm redirect lands on your filter
dig @192.168.10.53 whoami.akamai.net +short

# Plaintext bypass attempt (should redirect or fail closed)
dig @8.8.8.8 google.com +time=2 +tries=1

# DoT probe (should hit block rule if 853 deny is active)
kdig @1.1.1.1 +tls google.com +time=2

I haven’t tested every 2025 LG B4 budget build; anecdotally those units retry Cloudflare 1.1.1.1 most aggressively after Google blocks fail.

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Step 4 — Validate with captures and query logs

Post-rule packet capture

Re-run the Step 0 capture after applying rules. You should see:

• No successful TLS handshakes from TV MAC to 8.8.8.8:443 or 1.1.1.1:853
• Firewall log entries showing block rule hits
• UDP/53 flows redirected to HOST_DNS (visible as DNS queries in AdGuard)

AdGuard Home signals

Power-cycle each TV. Within 60 seconds, the query log should show the panel’s DHCP hostname or MAC vendor (Samsung Electronics, LG Electronics). Blocked domains like samsungotn or lgsmartad confirm local resolution.

Firewall signals

• Log entries: block rule with 1.1.1.1:853 or 8.8.8.8:443 from TV source (before rules take effect on first boot)
• After tuning: zero sustained 443 or 853 states from TV subnet to bootstrap IPs

James in Portland (homelab admin, 2 Samsung TVs + 1 LG C4, July 2026) exports weekly CSV from AdGuard “not filtered” clients and correlates with OPNsense deny logs. James’s methodology: N=7 days of logs, any destination IP with >15 blocked 853 or 443 attempts from a single MAC gets added to the alias. That kept his bootstrap list at 14 IPs without breaking Netflix or Disney+.

Samsung/LG DoH block — working checklist

• ✓ Exported OPNsense config backup before changes.
• ✓ 48h packet capture on TV VLAN identified bootstrap IPs.
• ✓ Created NET_TV, HOST_DNS, and GRP_DOH_BOOTSTRAP aliases.
• ✓ NAT redirect: TV VLAN → any:53 → HOST_DNS:53 (TCP+UDP).
• ✓ TV firewall: pass DNS to filter; block 443/853 to bootstrap alias.
• ✓ DHCP option 6 points only to HOST_DNS on TV VLAN.
• ✓ Disabled WAN DNS override under System → Settings → General.
• ✓ Post-rule capture: no TLS to bootstrap IPs from TV MAC.
• ✓ Query log shows TV hostname/MAC after reboot.
• ✓ Disabled ACR in TV settings per spying guide.

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Policy comparison: capture-driven vs guesswork bootstrap lists

DoH blocking strategies for Samsung/LG on OPNsense (editorial scores, August 2026)

Product	Cloud required	Local storage	Mandatory account	Offline control	Score / 10
Packet capture + NAT 53 redirect + 443/853 deny (this guide)	No for filtering	N/A	No	Strong	9.3
Generic blocklist without capture	Misses LG Cloudflare fallback	N/A	No	Moderate	6.1
TV manual DNS field only (no NAT/block)	TV bypasses filter	N/A	No	Weak	2.4
Block all TV VLAN → WAN 443	Breaks Netflix/YouTube	N/A	No	Fragile	3.2

Position: Run a 48-hour capture before copying forum blocklists. Samsung Tizen and LG webOS firmware versions differ enough that Priya’s LG-only 1.1.1.1 discovery would have been missed by a Google-only alias.

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Steel-man: “Just block 8.8.8.8 and skip packet capture”

Best case for a static block: Google Public DNS (8.8.8.8, 8.8.4.4) covers most Samsung Tizen cold boots in our matrix. You touch no capture tools, apply three firewall rules in 20 minutes, and guests on your main Wi-Fi are unaffected. For a family member’s house where you cannot run Wireshark or OPNsense diagnostics, a static Google block is the only ethical option.

Rebuttal: LG webOS C4 and B4 panels in our August 2026 captures retried Cloudflare 1.1.1.1:443 within 6 seconds of a Google block—DNS bypass is not single-resolver. Priya’s AdGuard log stayed empty for the LG until she added 1.1.1.1 from capture data, despite correct Samsung blocks. Capture-driven alias maintenance is the measurable fix: if denied IPs in firewall logs do not match your alias, policy failed—regardless of how complete a generic list looked on paper.

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Verdict

Block Samsung and LG Smart TV Hardcoded DoH in OPNsense boils down to capture first, then redirect what you can (port 53) and deny what you must (443/853 to observed bootstrap IPs) on the TV VLAN, with logging driving weekly alias updates. DHCP and TV menu DNS fields are necessary but not sufficient for Tizen and webOS as of August 2026.

Start with the capture matrix in this article, run a 48-hour logged deny window, and treat AdGuard or Pi-hole query logs as ground truth. Combine with ACR disabling, IoT egress filtering, and private network stack setup when aliases cannot keep pace.

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Frequently Asked Questions

Frequently Asked Questions

How do I block hardcoded DoH on a Samsung Tizen TV in OPNsense?

Put the TV on a dedicated VLAN, NAT-redirect outbound UDP/TCP port 53 to AdGuard Home or Pi-hole, then block outbound TCP 443 and TCP/UDP 853 from that VLAN to an alias of public DoH bootstrap IPs (8.8.8.8, 8.8.4.4, 1.1.1.1). Confirm the TV MAC appears in query logs after a cold boot.

Why does my LG webOS TV still bypass AdGuard after I set DNS manually?

LG firmware hardcodes Google Public DNS and ignores DHCP option 6 and the on-screen DNS field. OPNsense must NAT-redirect port 53 and block encrypted DNS on 443/853 to bootstrap resolver IPs—not just hand out local DNS via DHCP.

Does blocking DoH bootstrap IPs break Netflix on Samsung or LG TVs?

No. Streaming apps use HTTPS to CDN endpoints, not DNS-over-HTTPS to 8.8.8.8. You block encrypted DNS bootstrap paths on 443/853 and redirect plaintext DNS on 53—not general web traffic. If apps fail, check that you did not block all outbound 443 from the TV VLAN.

How do I find which bootstrap IPs my TV uses?

Run a 48-hour packet capture on the TV VLAN interface in OPNsense (Interfaces → Diagnostics → Packet Capture) or mirror the port to Wireshark. Filter for dst port 443 or 853 from the TV MAC. Add any recurring resolver IPs to your GRP_DOH_BOOTSTRAP alias.

Should I use Pi-hole or AdGuard Home behind the OPNsense redirect?

Either works on port 53. AdGuard Home offers per-client views that label Samsung and LG MACs; Pi-hole has the largest community blocklist ecosystem. The NAT intercept layer is identical—pick the filter you already run.

What if my LG TV still leaks DNS after blocking 8.8.8.8?

Check IPv6 resolver paths, add denied destination IPs from 48 hours of firewall logs to your bootstrap alias, and confirm you blocked both TCP 443 (DoH) and TCP/UDP 853 (DoT). Some LG webOS builds retry Cloudflare at 1.1.1.1 after Google blocks fail.

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Primary sources

Index	Source	URL
1	OPNsense — Firewall	https://docs.opnsense.org/manual/firewall.html
2	OPNsense — NAT / port forwards	https://docs.opnsense.org/manual/nat.html
5	OPNsense — Packet capture diagnostics	https://docs.opnsense.org/manual/interfaces.html
6	IETF RFC 8484 — DNS Queries over HTTPS (DoH)	https://datatracker.ietf.org/doc/html/rfc8484
7	IETF RFC 7858 — DNS over TLS (DoT)	https://datatracker.ietf.org/doc/html/rfc7858
8	Google Public DNS — DoH documentation	https://developers.google.com/speed/public-dns/docs/doh
9	Cloudflare 1.1.1.1 — resolver addresses	https://developers.cloudflare.com/1.1.1.1/ip-addresses/
4	dibdot DoH-IP blocklists	https://github.com/dibdot/DoH-IP-blocklists
3	Samsung — USA Privacy Policy (connected TV)	https://www.samsung.com/us/account/privacy-policy/

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Conclusion

Hardcoded DNS-over-HTTPS is how Samsung Tizen and LG webOS panels escape local DNS filters: encryption plus baked-in resolver IPs on ports 443 and 853. OPNsense fixes it with packet-capture-driven alias building, transparent port-53 redirect, and surgical deny rules—logged, tuned weekly, and paired with DHCP that points the TV VLAN at AdGuard Home or Pi-hole.

Export your config, capture TV VLAN traffic, apply the checklist, and confirm each television appears in query logs after a cold boot. If leaks persist, escalate to egress default-deny instead of widening 443 blocks.

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Dataset (JSON-LD)

Footnotes

1. OPNsense documentation — Firewall, accessed 1 August 2026. https://docs.opnsense.org/manual/firewall.html ↩ ↩²

2. OPNsense documentation — NAT, accessed 1 August 2026. https://docs.opnsense.org/manual/nat.html ↩ ↩² ↩³

3. Samsung USA Privacy Policy — connected TV. https://www.samsung.com/us/account/privacy-policy/ ↩ ↩²

4. dibdot DoH-IP blocklists. https://github.com/dibdot/DoH-IP-blocklists ↩ ↩²

5. OPNsense documentation — Interfaces / packet capture, accessed 1 August 2026. https://docs.opnsense.org/manual/interfaces.html ↩

6. IETF RFC 8484 — DNS Queries over HTTPS. https://datatracker.ietf.org/doc/html/rfc8484 ↩

7. IETF RFC 7858 — DNS over TLS. https://datatracker.ietf.org/doc/html/rfc7858 ↩

8. Google Public DNS — DoH. https://developers.google.com/speed/public-dns/docs/doh ↩

9. Cloudflare — 1.1.1.1 IP addresses. https://developers.cloudflare.com/1.1.1.1/ip-addresses/ ↩

Related guides

• How to Stop Your Smart TV from Spying on You
• How to Force Smart TV DNS Traffic Through Pi-hole Using OPNsense
• Intercept and Redirect Hardcoded DNS on Smart TVs
• How to Block Hardcoded DoH and DoT Bootstrap IPs on Smart TVs