Using MITRE D3FEND to strengthen you home network

D3FEND is a knowledge base of cybersecurity countermeasure techniques. In the simplest sense, it is a catalog of defensive cybersecurity techniques and their relationships to offensive/adversary techniques. It is designed for “Blue Team” Cybersecurity defenders to have a methodology to make their networks more secure. I am going to show you to take the techniques and shrink them down and apply them to our home network for Low, Medium and High Threat Models. Using MITRE D3FEND to strengthen you home network in this way will give us a framework to guide our efforts and keep on track.

What is a Cybersecurity Framework?

The simplest way of thinking about a frame work is to picture it as a template. Just like a document template helps you to write, this will help you to have a guide to setting up your network. It gives you things to think about when designing and implementing your network. This one was designed by the NSA (National Security Agency) who has some very intelligent and gifted Cybersecurity people. Taking what they suggest in defending a network is a good idea because they have a wealth of experience.

Five D3FEND categories:

1. Harden — make an exploitation harder (e.g., Network Traffic Filtering (D3‑NTF), Platform Hardening (D3‑PH), DNS Allowlisting (D3‑DNSAL), Executable Allowlisting (D3‑EAL)).
2. Detect — see what matters (e.g., Network Traffic Analysis (D3‑NTA), User Behavior Analysis (D3‑UBA), IP Reputation Analysis (D3‑IPRA), Per‑host DL/UL Ratio Analysis (D3‑PHDURA)).
3. Isolate — contain risk (e.g., Network Isolation (D3‑NI), Network Access Mediation (D3‑NAM), Outbound Traffic Filtering (D3‑OTF)).
4. Deceive — Trip up attackers (e.g., Standalone/Integrated Honeynet (D3‑SHN / D3‑IHN), Decoy Credentials (D3‑DUC), Decoy Files (D3‑DF)).
5. Evict — Recover & kick out the bad guys (e.g., Credential Rotation (D3‑CR, Reissue Credential (D3‑RIC), Restore Configuration/Software (D3‑RC/D3‑RS)).

We’ll implement these with pfSense on an x86 firewall or capable consumer router, plus a small Linux box (Raspberry Pi/NUC) as a “security node” for DNS, logging, and deception services.

Reference topology

This is what we are going to build. Your specific network will look different depending on your Threat Model and topology.

As you can see from the diagram, we are going to segment the network. This gives us more control over the management and the security. To create the VLANs (Virtual LANs) we need a switch that can handle this.

Switch/AP requirement: 802.1Q VLAN support and multiple SSIDs with VLAN tagging (most Unifi, TP‑Link Omada, OpenWrt APs).

Shopping list

We are going to reuse some of the things that we already have to save a bit of money. This is just to start out and to get everything setup, we can replace equipment with more appropriate and robust hardware when we choose. One of the best firewall hardware setups that I have found so far for home is the Protectli Vault . But when you are starting, it can be expensive, so try to reuse anything that you can.

• Firewall/Router:
• Option A: x86 mini‑PC (4–6 Intel NICs) + OPNsense (or pfSense CE)
• Option B: Consumer router that supports OpenWrt (or stock firmware with VLANs + DoT/DoH)
• Switch/AP: Managed switch with VLANs; AP that supports multiple SSIDs with VLAN tags
• Security node: Raspberry Pi 4/5 or old mini‑PC (Ubuntu/Debian)
• Storage: External SSD for encrypted backups (restic/borg)

Build steps by D3FEND tactic

• HARDEN (reduce attack surface & improve privacy)
  • Router OS hardening (Tasks: D3‑PH, D3‑SCP, D3‑SU)

OPNsense/pfSense

1.  Install latest release. During setup, disable WAN admin. Leave only LAN/management.
2.  Create a local admin with long passphrase + TOTP (D3‑MFA).
3.  System → Firmware: enable automatic security updates.
4.  System → Advanced → Admin Access:

• HTTPS only; disable HTTP, disable SSH on WAN.
• Restrict GUI to MGMT VLAN address.

5. System → User Manager: create a “break‑glass account” printed to a sealed envelope.This is an admin account that is used only in emergencies and is super secure.

Segmented VLANs & SSIDs

Common Steps:

1. Create VLANs: 10=TRUSTED, 20=IOT, 30=GUEST, 40=MGMT, 50=SERVICES.
2. Trunk VLANs between router ↔ switch ↔ AP. Tag SSIDs to VLANs.

OPNsense/pfSense

• Interfaces → Other Types → VLANs: add VLANs on LAN parent.
• Interfaces → Assignments: create OPT interfaces per VLAN, set static RFC1918 subnets.
• Services → DHCPv4: enable per‑VLAN with small leases; set DNS to Security Node IP (VLAN 50).

 

Default‑deny inter‑VLAN rules  

Policy

• Intra‑VLAN: allow established/related; block lateral movement.
• Inter‑VLAN: DENY any→any by default. Add minimal allow rules:
• IOT → Internet: allow DNS to Security Node, allow NTP, allow vendor cloud only by FQDN/IP lists.
• GUEST → Internet: allow DNS to Security Node and HTTPS only; deny RFC1918 destinations.
• TRUSTED → SERVICES: allow DNS, syslog, VPN, update mirrors.

OPNsense/pfSense: Firewall → Rules per interface; add Block Private Networks on WAN. Use Aliases for country blocks or vendor IPs.

 

Private, encrypted DNS with policy

Security Node (AdGuard Home or Unbound + RPZ)

1. Install AdGuard Home (AGH) on the Services VLAN host.
2. Configure upstream to privacy‑oriented DoT/DoH (Quad9, NextDNS) and enable DNSSEC validation.
3. Enable Blocklists (malware, trackers) and create allowlists for critical services (banking, work tools).
4. Per‑VLAN/Client rules:

• IOT: block *.lan lookups to avoid snooping; allow only vendor FQDNs as needed.
• Guest: adult‑content + telemetry blocklists.

5. Export per‑VLAN analytics to the SIEM‑lite (see 4.2.3).

 

Network enforcement

• Force all DNS to Security Node: block outbound 53/853/443 DoH except to your upstreams; NAT‑redirect rogue 53 to Security Node.

Strong Wi‑Fi 

• WPA3‑SAE where possible; fallback to WPA2‑AES only.
• Unique per‑SSID long passphrases; rotate guest key monthly.
• Disable WPS; hide management SSID; restrict AP management to VLAN 40.

 

Endpoint hardening

• Windows: Enable Smart App Control (Win11), ASR rules, BitLocker, Credential Guard; restrict admin use.
• macOS: Full Disk Encryption (FileVault), App Store‑only or notarized apps, Lockdown Mode if high‑risk.
• Mobile: Use app‑store only; per‑app VPN for high‑risk travel; strong device PIN; disable ad ID.

Outbound privacy (split‑tunnel VPN)

• Router‑level WireGuard client to a trusted provider. Policy‑route only sensitive devices (TRUSTED VLAN) via VPN; keep streaming/IoT on clear path to avoid geo/latency issues. Create kill switch rules so VPN‑routed clients cannot reach WAN without the tunnel.

 

DETECT

The goal is to see the important information and not to be flooded with all of the things that the system is seeing and miss the important bits of information.

Inline IDS/IPS

OPNsense

1. Services → Intrusion Detection: enable Suricata in IPS mode on WAN + VLAN interfaces.
2. Subscribe to ET Open/Telemetry rules; enable DNS/DoH/IoT‑related rulesets.
3. Set Promisc off (inline) and Hyperscan on (if supported) for performance.

NetFlow/sFlow lite 

• On OPNsense: Reporting → NetFlow enable flow exporter to Security Node (e.g., nfdump + go‑flow collector).
• On OpenWrt: softflowd exporting to the Security Node.

SIEM‑lite & dashboards

• On the Security Node:

1. Install Vector (or Filebeat) to ship logs (firewall, Suricata, AdGuard) → OpenSearch/Grafana stack.
2. Build dashboards: Top talkers, New domains seen, Denied connections, Suricata hits.
3. Create alerts:

• New device MAC on any VLAN (rogue join).
• High DNS entropy / domain flux.
• Per‑host DL/UL ratio anomaly (D3‑PHDURA) > e.g., 10× baseline.

Reputation & certificate checks

• Enable IP/domain reputation lookups in IDS; log TLS SNI + cert fingerprints (Zeek optional) for anomaly triage.

 

ISOLATE 

Containment by design – designing your network in containers and micro containers to super segment it for management and security.

Micro‑perimeters 

• Create device groups via aliases: iot-cams, iot-speakers, workstations.
• Apply egress policies per group, e.g., cameras → allow only tcp/443 to vendor cloud CIDR, NTP, and deny RFC1918.

Just‑enough admin paths

• Restrict SSH/HTTPS management to MGMT VLAN and to a jump host.
• Use port‑knocking or single‑packet auth (e.g., WireGuard management only) instead of exposing ports.

Application isolation for risky workloads

• Browse unknown sites inside Firefox Temporary Containers, Chromium profiles, or a disposable VM (Qubes/WSL2 VM) for admin tasks.

DECEIVE

Turn attackers into telemetry so you can see what the bad guys are up to.

Low‑interaction honeypots

• On the Security Node, deploy Cowrie (SSH/Telnet), Honeytrap (common ports) on a dedicated “decoy” IP in SERVICES VLAN.
• Expose only from IOT/GUEST networks via firewall NAT to make scans hit decoys, not real hosts.

Honeytokens

• Plant canary credentials in a private Git repo (never used by you) and monitor for use.
• Drop decoy documents (e.g., Passwords-NEW.kdbx) with embedded web beacons in a read‑only share. Any access creates an alert.

NetFlow/sFlow lite

• On OPNsense: Reporting → NetFlow enable flow exporter to Security Node (e.g., nfdump + go‑flow collector).

IEM‑lite & dashboards

• On the Security Node:

1. Install Vector (or Filebeat) to ship logs (firewall, Suricata, AdGuard) → OpenSearch/Grafana stack.
2. Build dashboards: Top talkers, New domains seen, Denied connections, Suricata hits.
3. Create alerts:

• New device MAC on any VLAN (rogue join).
• High DNS entropy / domain flux.
• Per‑host DL/UL ratio anomaly –  10× baseline.

 

EVICT

After you find a breach this is a response & recovery that you can actually do.

Identity hygiene

• Password manager with unique credentials + MFA everywhere.
• Compromise playbook: revoke tokens (email/OAuth), rotate router/account secrets, re‑issue WireGuard keys.

Gold‑image + config backups

• Export router config after each change; store encrypted offline.
• Keep system images (Clonezilla/bare metal image) for critical machines; test restores quarterly.

Clean‑wipe policy

• On confirmed compromise: back up → wipe → reinstall; never attempt “surgical cleaning” on a critical host, you will miss something vital.

 

Conclusion

I know that this post was incredibly long. I appreciate you going through it and sticking with me. This was more than just an intellectual exercise.  The purpose was to take a framework that is very high level and bring it down to household level so that it could be used for anyone.

The details that I presented, though long and sometimes technical, can be achieved by anyone by just following along. I do hope that this spurs your imagination as to what is possible when you put some of these into play for your own personal security and privacy.

Cybersecurity and privacy for yourself and family is not a destination, it is a journey that is long and always there. You can take some or all of the concepts in this and modify them to your own Threat Model and lifestyle. There are no off the shelf solutions that will fit everyone.

 

 

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