One of the best approachable writeups I've found on getting started in reversing embedded devices is an old gem from Matasano. Retsaot is Toaster, Reversed: Qui

One of the best approachable writeups I've found on getting started in reversing embedded devices is an old gem from Matasano. Retsaot is Toaster, Reversed: Quick 'n Dirty Firmware Reversing - http://www.woodmann.com/forum/archive/index.php/t-11707.html http://www.woodmann.com/forum/archive/index.php/t-11707.html That should give you a little bit of a feel for it. Its a fun rabbit hole to spend a few years down.