STM32 Sniffer for BLE User guide

This article provide help about how to use the STM32 Sniffer for Bluetooth^® LE with Wireshark. It is supposed that you've already installed the sniffer, if it is not the case, you can follow this guide.

1. Starting the capture

Plug your sniffer board and open Wireshark.

1.1. Optional configuration

• In Wireshark, click on the wheel on the left of the STM32 sniffer interface to open the interface configuration menu.
• The channel index parameter is the channel on which the sniffer will listen when started. It can be changed later on the fly. By default it is channel index 39.
• This is the channel index, not the frequency index. e.g (primary adverstising channels indexes are 37, 38 and 39).

Optional parameter

1.2. Launching the capture

To start the capture:

Click once to select the interface

Click on start capturing

or

Double click on the interface

Optional parameter

1.3. Sniffer started

You should now see the advertising packets on the channel you configured.

By default on startup the target BD address is set to 00:00:00:00:00:00, meaning that no target is set so packets from every devices are displayed.

Optional parameter

2. Following a connection

Once the sniffer is started is reports advertising, scan requests and scan requests of all devices. You can then set the BD address of your target device that you want to follow when a connection to it occur.

Set the target BD address

Apply changes

Setting a target to follow

Now you should only see:

• Advertising and scan responses packets from the target
• Scan requests to the target
• Connection packets from and to the target

Target set

If after setting the target there is no more packets incoming either:

• There is no device with this BD address advertising on this channel
• The sniffer has not received the command, set again the target (you will need to make a change to be able to apply changes. Just delete the last number and reenter it)

Now if a device connect to your target and the sniffer intercept the CONNECT_IND packet you will start to see the communications between the two devices.

Information

As the sniffer only listen on one advertising channel it may not intercept the connection request on first try if the request was made on another channel. In this case, reconnect to your target. You can also see the multiple interfaces capture to improve the connect request interception success rate.

Connection intercepted

Now you have some additional data:

• The direction column indicates the direction of the packets
• The color of the lines is alternating for each connection event

If the connection is terminated or if the sniffer loose it, it will return to the advertising channel you have configured before.