The following tutorial is made for updating Korlan USB2CAN firmware on Linux operating system. You can get the firmware here
1. Install dfu-util (>= 0.9)
sudo apt-get install dfu-util
2. Extract the firmware archive
unzip usb2can2.1.zip
3. Switch to internal bootloader using the set_dfu utility provided with the firmware:
sudo ./set_dfu
4. Flash new firmware as root:
sudo dfu-util -a 0 -s 0x8008000 -D USB2CAN-2.1.bin
5. Power-cycle the device after firmware update.