Download from vendor

wget http://vendor.com/firmware/update.bin

Extract from device via debug interface

UART console access

screen /dev/ttyUSB0 115200

Copy firmware partition

dd if=/dev/mtd0 of=/tmp/firmware.bin

Extract via network protocols

TFTP during boot

HTTP/FTP from device web interface

### Hardware Methods

UART access - Serial console connection JTAG/SWD - Debug interface for memory access SPI flash dump - Direct chip reading