USB device access rights

You can allow access to the DFU device

49-stm32-dfuse.rules
# This is udev rules file (place in /etc/udev/rules.d)
# Makes STM32 DfuSe device accessible to the "plugdev" group

ACTION=="add", SUBSYSTEM=="usb", ATTRS{idVendor}=="0483", ATTRS{idProduct}=="df11", MODE="664", GROUP="plugdev"

Copy this file to udev rules directory:

sudo cp 49-stm32-dfuse.rules /etc/udev/rules.d/
sudo udevadm control --reload-rules

or as root

cd /etc/udev/rules.d/
cat << OI > 49-stm32-dfuse.rules
# This is udev rules file (place in /etc/udev/rules.d)
# Makes STM32 DfuSe device accessible to the "plugdev" group

ACTION=="add", SUBSYSTEM=="usb", ATTRS{idVendor}=="0483", ATTRS{idProduct}=="df11", MODE="664", GROUP="plugdev"
OI
udevadm control --reload-rules

Port preparation

Modemmanager quite strongly interfere with serial lines, here is how you can remove it:

sudo apt-get remove --purge modemmanager

Required modules

sudo apt-get install python3-tk
sudo apt-get install python3-usb