I'm kind of in the mood to implement some CCSDS standards. "Standard Formatted Data Units" (never a more generic name) is a classic, and it even comes with an honestly extremely well-written tutorial (i didn't even exist properly when this was published!). I haven't had the chance to do Rust in a while, soo.... screw it, let's write some SFDU-processing Rust.
(if you have another favorite standard please shout at me. not RFC 854 or RFC 1143 though, i have bigger plans for telnet)