Introduction
In today’s connected homes, dozens of devices—from smart TVs to embedded development boards—are constantly sending and receiving data. Often, this includes tracking scripts, telemetry, and ads that clutter web pages and slow down connections. While browser-based ad blockers can provide some relief, they only work on individual machines. For embedded developers and home server enthusiasts, there’s a better way.
Pi-hole is a DNS-based filtering tool that acts as a local sinkhole for advertisements, malware domains, and telemetry. It blocks unwanted content at the network level, meaning every device on your network benefits—from your smartphone to your ESP32 test rig.
In this guide, we will set up Pi-hole on a Raspberry Pi Zero W, creating a lightweight, always-on DNS server that blocks ads and gives you insight into which devices are talking to the internet.
Why Use Pi-hole?
Benefits
- Network-wide ad blocking: Automatically filters out ads for every connected device.
- Improved speed and privacy: No more waiting for ad trackers to load.
- Device monitoring: See what domains each device is querying.
- Embedded-friendly: Helps monitor outbound connections from IoT prototypes.
- Energy-efficient: Runs 24/7 on the Pi Zero W using just 0.5–1W.
Why the Pi Zero W?
Despite being the smallest and cheapest Pi model with Wi-Fi, the Pi Zero W has more than enough power to run Pi-hole for home or lab use. Unless you’re servicing hundreds of clients simultaneously, the performance will be solid.
Prerequisites
Hardware
- Raspberry Pi Zero W
- 8GB or larger microSD card
- 5V micro USB power supply
- Wi-Fi network
- Computer with SSH or terminal access
- (Optional) USB-to-ethernet adapter if you prefer wired setup
Software
- Raspberry Pi OS Lite (headless setup preferred)
- Pi-hole installation script (provided by the developers)
- Access to your router for DNS/DHCP changes
If your Pi Zero W is already set up headlessly, you can skip the OS flashing section and go directly to the Pi-hole installation.
Step 1: Prepare the Raspberry Pi
Ensure your Raspberry Pi OS is up to date:
sudo apt update && sudo apt upgrade -y
Set a static IP address so that other devices can reliably use it as their DNS server.
sudo nano /etc/dhcpcd.conf
Add the following at the bottom:
interface wlan0
static ip_address=192.168.1.250/24
static routers=192.168.1.1
static domain_name_servers=1.1.1.1 8.8.8.8
Adjust the IP address to fit your network configuration. Save and reboot.
sudo reboot
Confirm the new IP with:
ip a
Step 2: Install Pi-hole
Pi-hole provides a convenient automated installation script.
Download and Run the Script
curl -sSL https://install.pi-hole.net | bash
You’ll be guided through an interactive setup. Key steps include:
- Static IP confirmation: Accept the detected IP address if correct.
- Upstream DNS provider: Choose from Cloudflare, Google, OpenDNS, or custom.
- Blocklists: Use the default lists (you can add more later).
- Web interface: Enable this unless you prefer CLI-only.
- Admin password: Note the default password provided at the end.
Once complete, access the web dashboard at:
http://<your-pi-ip>/admin
Step 3: Configure Your Network to Use Pi-hole
For Pi-hole to be effective, client devices must use it as their DNS server.
Option 1: Set DNS in Router (Recommended)
Log in to your router’s admin interface and set the LAN-side DNS to your Pi’s IP address (e.g., 192.168.1.250). This makes all connected devices use Pi-hole automatically.
Note: Some routers also provide DHCP services. If you're using Pi-hole as the DHCP server, disable DHCP on the router to avoid conflicts.
Option 2: Set DNS on Each Device
For test setups or limited use, you can manually configure DNS on individual machines or development boards:
- On Windows/macOS: Set the DNS server in your network settings.
- On ESP32/nRF/STM32 devices: Configure the DNS field in your TCP/IP stack or SDK settings.
Step 4: Using the Pi-hole Dashboard
Navigate to the admin dashboard and log in using the password from setup.
Key Features
- Query Log: See which domains were requested and by which clients.
- Top Clients: Identify noisy or chatty devices.
- Blocked Domains: View what’s being filtered.
- Whitelist/Blacklist: Manually control filtering behavior.
- Graphs & Stats: Visualize traffic volume and blocking effectiveness.
Pi-hole provides a surprisingly in-depth view of DNS activity, offering real-time insight into all devices on your network—including embedded development boards.
Step 5: Advanced Use Cases for Embedded Developers
Monitor Embedded Device Traffic
Use Pi-hole to monitor the network behavior of devices you build. Many SDKs (like ESP-IDF, Zephyr, or Arduino-based Wi-Fi stacks) make calls to update servers or resolve DNS names even in production firmware.
By examining the DNS queries:
- Spot hidden calls to analytics or external endpoints
- Verify OTA update URLs are being correctly requested
- Detect unexpected behavior (e.g., repeated NTP failures)
This kind of passive monitoring is useful when building secure, auditable IoT devices.
Control Device Access
You can block domains used by firmware for OTA or telemetry. For example:
pihole -b ota.vendor.com
This is a quick way to test how your firmware responds to blocked endpoints without modifying code or using firewall rules.
Run Headless
You don’t need to keep the dashboard open. Once Pi-hole is set up, it runs as a background service and logs everything automatically. You can SSH in periodically or use the dashboard to retrieve statistics.
Performance Tips
Despite the Pi Zero W's limited specs, it performs well as a DNS sinkhole with a few considerations.
Reduce Logging
Disable query logging or limit retention to improve performance and SD card longevity:
pihole logging off
Or reduce log retention in the web dashboard under Settings > Privacy.
Use a Quality microSD Card
Choose a name-brand card (SanDisk, Samsung, Kingston) rated for high endurance or surveillance applications. This reduces risk of corruption under 24/7 load.
Monitor System Resources
Use htop or top to check CPU and memory usage:
htop
Pi-hole itself consumes less than 20MB RAM and under 1% CPU on average during idle use.
Maintenance and Security
Update Pi-hole
Run this command periodically to stay current:
pihole -up
Secure the Admin Panel
Change the admin password if needed:
pihole -a -p
Restrict access to the dashboard by IP range or use router-level firewall rules.
Back Up Configuration
Pi-hole provides export/import tools for settings and blocklists. Backup your configuration manually or with:
cp -r /etc/pihole/ ~/pihole-backup/
Troubleshooting
DNS Not Working?
Ensure your Pi-hole has a working upstream connection (check /etc/resolv.conf) and that clients are using it as their primary DNS.
Stats Not Updating?
Try restarting the DNS resolver:
pihole restartdns
Web Interface Not Loading?
Ensure the lighttpd web server is running:
sudo service lighttpd status
Restart it if needed:
sudo service lighttpd restart
Conclusion
Installing Pi-hole on a Raspberry Pi Zero W is one of the most impactful improvements you can make to your home network, especially if you are a developer, tinkerer, or embedded systems engineer. With minimal effort and low power requirements, you gain a powerful, centralized DNS filtering system that not only blocks ads but also gives you deep visibility into device behavior.
Whether you are trying to keep your home network clean or need a simple tool to audit your firmware’s DNS activity, Pi-hole on the Pi Zero W delivers powerful capabilities in a small package. It works quietly in the background, improves your experience across all devices, and gives you control over your own infrastructure.
In the next article, we will explore how to combine Pi-hole with a local OTA firmware server—letting you host, monitor, and control your embedded devices entirely from your Raspberry Pi.