Adding a Second Wireless Adaptor to a Raspberry Pi for Network Monitoring

Alasdair Allan
10 min readMar 12, 2018

It used to be a hassle to get a wireless adaptor working with the Raspberry Pi. But these days both the Raspberry Pi 3 and the Raspberry Pi Zero W have one already on board, and getting wireless networking working is much easier.

The Raspberry Pi 3 already has an on-board wireless adaptor.

But what if you want to add a second wireless adaptor in monitor mode?

What is Monitor Mode?

Monitor mode allows a computer with a wireless network interface controller to monitor all traffic received from the wireless network. But unlike the more commonly used promiscuous mode, monitor mode allows packets to be captured without having to associate with an access point or ad-hoc network first.

What Adaptor Should I Use?

If you’re interested in using monitoring mode you’ll need to add a second USB WiFi dongle to your Raspberry Pi since the BCM43438 WiFi chipset used on the Raspberry Pi 3 does not currently support monitoring mode. However additional USB wireless adaptors are cheap and readily available, and if you have a need to, you can easily add more than one.