netdiff performs diff across network links.
Takes two arguments which may be host:path pairs in the style of ssh/scp, make temporary local copies as needed, applies diff(1). All options are passed to diff(1).
It’s not fast over large trees, but quite useful if you need to (for example) diff /etc across hosts on a LAN.
Written in pure POSIX shell; no dependencies other than scp(1) and diff(1),