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.