If you are a dual-boot user running Fedora 43 and Windows, you have certainly encountered this frustrating issue: you pair your Bluetooth soundbar on Linux, then on Windows, but when you return to Linux, the connection is lost.

Disclaimer: The MAC addresses and the Link Key used in this tutorial (e.g., 88:C9:E8... and A5AF8E...) are fictional examples. You must identify and use the specific values belonging to your own hardware.

The Problem Explanation

The technical reason is simple: your Bluetooth hardware has a unique MAC address. When you pair a device, a Link Key (a unique security token) is generated. Windows and Linux each create their own different key. The soundbar, seeing the same MAC address but a different key, rejects the connection for security reasons.

To solve this, we must force Linux to use the exact same Link Key as Windows. Here is how to do it 100% from Linux, without needing to reboot into Windows.

1. Install the Necessary Tools

We need to access the Windows Registry files while they are “offline.” We will use chntpw (a tool to modify the Windows SAM/Registry) and ntfs-3g to mount the partition.

On Fedora, open your terminal and run:

sudo dnf install chntpw ntfs-3g

2. Mount the Windows Partition

First, identify your Windows partition (look for the NTFS drive) using lsblk. Then, mount it in read-only mode to ensure data safety.

sudo mkdir -p /mnt/windows
# Replace /dev/nvme0n1p3 with your actual partition name
sudo mount -t ntfs-3g -o ro /dev/nvme0n1p3 /mnt/windows

3. Locate the Keys in the Windows Registry

Windows stores Bluetooth keys in a binary hive located at C:\Windows\System32\config\SYSTEM.

Navigate to the directory and open the registry editor:

cd /mnt/windows/Windows/System32/config
sudo chntpw -e SYSTEM

Once the interactive prompt (>) appears, navigate to the Bluetooth parameters:

> cd \ControlSet001\Services\BTHPORT\Parameters\Keys
> ls

You will see a subkey named after your PC’s Bluetooth adapter MAC address. Enter that folder:

> cd [YOUR_ADAPTER_MAC]
> ls

You will now see the MAC addresses of your paired devices. To get the key for your soundbar, use the hex command followed by the device MAC address:

> hex 88c9e8bb6d14

The output will display a series of 16 bytes. Example output: A5 AF 8E 19 BA C8 CE F3 F0 F2 ED 6B DC 9A CF 4B

Copy this string and remove the spaces. This is your Windows Link Key.

5. Update the Linux Bluetooth Configuration

Now we must inject this key into Fedora’s configuration files. Linux stores these in /var/lib/bluetooth/. Note that Linux directory names use upper case and colons for MAC addresses.

Open the info file for your device:

sudo nano /var/lib/bluetooth/[ADAPTER_MAC]/[DEVICE_MAC]/info

Find the [LinkKey] section and update it with your Windows key:

[LinkKey]
Key=A5AF8E19BAC8CEF3F0F2ED6BDC9ACF4B
Type=4
PINLength=0

6. Test the Connection

To apply the changes, you must restart the Bluetooth service so it reloads the modified configuration file:

sudo systemctl restart bluetooth

Now, try to connect to your soundbar:

bluetoothctl connect [DEVICE_MAC]

If it connects successfully, you can now switch between Fedora and Windows without ever needing to re-pair your audio equipment again. Finally, do not forget to unmount your Windows partition:

sudo umount /mnt/windows