In my last blog about connection shutdowns in curl, I was a bit vague about why ending TCP connections via FIN is much preferable to a RST. Dan Fandrich provided me with the links to that necessary wordings from the TCP standards to explain that in more detail. Note: while I say “detail”, it seems worthy to state that I try to explain the topic without the need to understand everything about TCP. Real network gurus might despair at some shortcuts taken here. I apologize.