Why you should make use of Virtual LAN (Guest Wi-Fi)

Guest Wi-Fi, or more precisely virtual LAN, is a feature of many Internet routers. It adds another wireless networking option, which is fully separated from the main local network.

The term Guest Wi-Fi refers to one of its primary purposes: to allow guests to connect their devices to the Internet using a wireless connection. There is more to virtual LAN than that, however.

Many modern devices ask for Internet connectivity. Some work perfectly well without, but others require this connectivity to be of any use. Basic examples of devices that fall into the latter category include Amazon Fire TV and Alexa, most Google Home devices and most virtual assistant services.

Many devices support Internet connectivity; these can be printers, scanners or web cameras, but also a growing assortment of, often, perplexing devices that include toaster ovens, toothbrushes or refrigerators.

All of these devices are on the same local network by default, which is bad.

A story of a Printer, Amazon and Printer Ink emails

A user posted an interesting story on Hacker News the other day. They revealed that they have been receiving emails from Amazon about printer ink reorders frequently. Amazon knew about the printer and ink consumption, but the user did not know how.

The user had an Amazon Echo device connected to the local network. It turned out that Amazon’s device was picking up information that the printer provided to any device of the local network. In other words, Amazon knew when and what the user printed. It used the information to estimate printer ink use to send printer ink offers to the user.

Guest Wi-Fi may prevent this

The use of a virtual LAN might prevent this data leakage from happening. You would have to enable the guest Wi-Fi option in the router and connect one of the two devices to it.

Not all routers support virtual LAN functionality and some only with limited functionality. You may open the router’s dashboard on the local network to check if you find Guest Wi-Fi or a similarly named feature there.

The only step left is to connect the devices that you want to isolate to the new wireless network, effectively cutting it off from the local one.

These devices retain Internet connectivity, but they can’t communicate with devices that are not connected to the Guest Wi-fi anymore.

There may be other solutions, depending on setup. Some devices can be connected using cables. If you don’t require Internet connectivity for a device, say a printer, you could connect it using cables only. This would remove an attack vector as well.

The advantages and disadvantages of Guest Wi-Fi

Virtual networks offer several advantages over connecting all devices to a single network:

• Connected devices are isolated from the rest of the network, which means that they are blocked from interacting with the home network. This offers several advantages:
  • The devices can’t collect personal data anymore from the main network.
  • Attacks that exploit issues in Guest Wi-Fi devices can’t penetrate the local network anymore.
• Another key point is that you don’t need to share the main wireless LAN password with guests.
• Last but not least, you may turn off wireless access for these devices at any time.

Even though Guest Wi-fi offers advantages, it is equally important to understand certain disadvantages.

• Most routers support just a single virtual network. If you connect multiple devices to it, these devices may share information. Ideally, you’d put all IoT devices on a separate VLAN.
• Some devices may require access to local data or other devices. If you want to cast from your PC to your TV, you need them on the same network. Others may flat out refuse to work without home network connection.
• The configuration options of virtual networks may be limited.

Closing Words

It is a good idea to enable Guest Wi-Fi, if supported by the router. Some IoT device connections may be switched to improve security and privacy. While it may not be possible to migrate every device, it may also be a good idea to assess the status quo of all devices with Internet connectivity. Do all of these require an active Internet connection?

Now You: do you use Guest Wi-Fi on your network?