I am using the newest Ubuntu 20.04, and all software were updated.

After installation of system, U disk can be used without any problem. After installation of many other software, U disk can not be recognized. I am sure the driver was installed. When I run "`lsusb`", I can find the usb disk

```
Bus 001 Device 005: ID 0951:1666 Kingston Technology DataTraveler 100 G3/G4/SE9 G2

```

When I run "`dmesg`", it shows

```
[241620.374470] usb 1-1.3: Device is not authorized for usage
[241637.411899] usb 1-1.3: USB disconnect, device number 4

```

I edited the "`org.freedesktop.devicekit.udisks.policy`", change "`allow_any`" to yes and still not work!

Later, I found the problem is that usbguard blocks the usb-device.

Find out the id of device by "`usbguard list-devices`" and use "`usbguard allow-device XX`". But how can it work automaticly?