A free kids' game can make 40 tracking calls per minute. Not to run the game — to profile the child holding the tablet.

You can't see those calls. But your network can. And if you catch them in one place, you get a live "wall of shame" listing every company reaching into your child's screen. Here's how to build it in an evening.

The idea

Every app phones home through DNS — the internet's address book. When a game loads an ad tracker, it first asks "where is doubleclick.net?" If you run your own DNS server, you see that question. And you can refuse to answer it.

We'll use Pi-hole. It's a self-hosted DNS filter that logs every request and blocks the junk. It runs on almost anything — an old laptop, a Raspberry Pi, even a spare mini PC in a drawer.

Step 1: Install Pi-hole

On any Linux machine on your home network, run:

curl -sSL https://install.pi-hole.net | bash

The installer walks you through it. Pick a blocklist when asked — the default is fine. At the end it gives you an admin web address and a password. Write both down.

Step 2: Point the tablet at it

Open the tablet's WiFi settings. Find the connected network, tap it, and change DNS from "automatic" to "manual." Enter the Pi-hole machine's local IP (something like 192.168.1.50).

Save. The tablet now asks your server for every address it needs.

Step 3: Watch the wall

Open the Pi-hole admin page in a browser. Go to Query Log. Hand the tablet to your kid and let them open their usual games.

Within seconds the log fills. You'll see names like app-measurement.com, graph.facebook.com, adcolony.com, unity3d.com. Each line is one attempt to track, profile, or advertise.

The Top Blocked chart is your wall of shame — a ranked list of the worst offenders, updated live.

Step 4: Block the worst

Most trackers are blocked automatically. For any that slip through, click the domain in the log and hit Blacklist. Done. That company never reaches the tablet again.

Want every device covered? Set the Pi-hole IP as DNS on your router instead of the tablet. Now the whole house runs through it.

A warning

Don't block blindly across all devices. Some apps break if a required domain is refused. If a video won't load, check the log, find what got blocked, and whitelist it. Pi-hole makes this a two-click fix.

The takeaway

Tonight: install Pi-hole, point one tablet at it, and open a game. The list of names that appears is the exact set of companies watching your child. Blacklist the top five. That's five fewer strangers in the room.