I remember learning the basics of networking in 1989 from the "The Linux Network Administrator's Guide", which is/was part of the Linux Documentation Project.

I remember learning the basics of networking in 1989 from the "The Linux Network Administrator's Guide", which is/was part of the Linux Documentation Project. It focuses on the software aspect of things, but IMHO it is still a good read for introduction. My favorite book on the topic (covers hardware and software) is: "Computer Networks" by Larry L. Peterson & Bruce S. Davie.