Take stock of your network
You can’t protect what you don’t know is there. Most homes have far more on their network than the phones and laptops people think of first: a TV, a printer, a doorbell, a smart plug, the games console, a relative’s tablet that joined once. In this lesson you’ll list every one of them, identify the ones you don’t recognise, and decide where each belongs. Everything else in this course builds on that list.
In this lesson
- Make a complete list of the devices on your network
- Identify unknown devices from their MAC address
- Sort every device into main network, guest network or remove
You’ll need: your router’s admin page open. If you haven’t logged in before, Meet Your Router shows how and where to find the device list.
Why the list matters
Every device on your home network can usually reach every other one. That’s convenient: your laptop can print, your phone can cast to the TV. But it also means the weakest device sets the level of security for all of them. A cheap camera that hasn’t had an update in years sits on the same network as the laptop with your bank logins. The list you make now is how you’ll decide, in Lessons 3 and 6, which devices to move somewhere safer.
Try it yourself · part 1
List everything that’s connected
- In your router’s admin page, open the list of connected devices. It’s usually called Attached devices, Connected devices, Device list or DHCP clients. If you have a mesh system, the list is usually in its phone app instead.
- For each device, write down three things: the name the router shows, its MAC address (six pairs of letters and numbers, like
A4:83:E7:12:34:56), and whether it’s connected by Wi-Fi or cable. - Now go through the list and put a name you recognise next to each one: “Dad’s phone”, “living-room TV”, “printer”. Many will be obvious from their names. Leave the rest blank for part 2.
- Some devices only appear while they’re switched on. If you know there’s a games console or a tablet that’s off right now, add it to your list anyway.
What a MAC address can tell you
Every network card leaves the factory with a hardware address, its MAC address. The first half identifies the company that made the network chip, which is often enough to work out what a device is: a laptop, a TV, a smart plug. There’s one catch. Most phones, and many laptops, now make up a random “private” address for each Wi-Fi network they join, so that shops and airports can’t track them from place to place. Those addresses have no manufacturer at all.
Try it yourself · part 2
Identify the unknown devices
- Copy the MAC addresses of every device you couldn’t name, one per line.
- Paste them into the MAC Address Lookup and click Look up. It checks them against the official IEEE registry inside your browser; the addresses aren’t sent anywhere.
- Read the result for each one:
- A manufacturer name, marked HARDWARE: the real factory address. A chip maker like Espressif, whose chips are in many smart plugs and bulbs, usually means a gadget like that; a TV or printer brand usually means just that.
- RANDOMISED / PRIVATE: an address made up by software, almost always a phone, tablet or laptop using a private Wi-Fi address. There’s no manufacturer to find.
- For a private address, check the phones in your home: on an iPhone, open Settings, Wi-Fi, tap ⓘ next to your network and look at Wi-Fi Address; on Android, open your network’s details and look for the MAC address. A match solves it.
- Still can’t place one? Switch off devices one at a time and see which entry disappears from the list.
Try it yourself · part 3
Sort every device
Go through your list and give each device one of three labels. You’ll act on them later in the course.
| Label | What goes there |
|---|---|
| Main network | The devices you trust and keep updated: your computers and phones, and anything that holds files you care about, like a home server. |
| Guest network | Smart plugs, bulbs, cameras, speakers, TVs, games consoles, and visitors’ phones: things that only need the internet, not your other devices. |
| Remove | Anything you no longer use, or can’t identify after the checks above. If it’s yours and you don’t need it online, disconnect it. |
Keep this list. You’ll use it in Lesson 3, when you set up the guest network, and in Lesson 6, when you deal with smart devices one by one.
Key takeaways
- Your router’s device list shows everything that’s connected; most homes have more than they expect.
- The first half of a MAC address identifies the maker of the network chip.
- RANDOMISED / PRIVATE addresses are almost always phones or laptops using private Wi-Fi addresses.
- Sort every device: main network, guest network, or remove.
- An unknown device you can’t explain is a reason to change your Wi-Fi password, not to panic.
Check yourself
Three questions. Pick one answer each and you’ll see why.
1. The MAC lookup says an unknown device is RANDOMISED / PRIVATE. What is it most likely to be?
2. Why does it matter which network a cheap smart plug is on?
3. After every check, there’s still one device you can’t identify. What’s the sensible next step?
Want the full checklist this course works through? How to Secure Your Home Network lists every setting in one place.
This lesson is part of the free course Secure Your Home Network, licensed under CC BY-NC-SA 4.0: you may share and adapt it for non-commercial use, with credit to ExamineIP and a link to the original.