Beej's Guide to Network Programming

+1 for Beej’s. I took a networking course at UCLA that used it as the textbook and it was great.

Upvoted for beej. An absolute must read for anyone that works with a TCP/IP based stack.

I think Beej's Guide to Network Programming is IMO hands down the best resource I've come across: https://beej.us/guide/bgnet/ It also doubles as a very great introduction to C, if that something you're interested in. It's funny because both C and socket level programming are often a barrier, or at least they were for me. It's an attestant to the quality of Beej's guide that he introduces both simultaneously, and makes it very approachable. This is one of those sources that helped me disproportionately grow as a programmer in a short period of time.

This and the Ross/Kurose one are definitely the canonical textbooks, but Beej's Guide is a lighthearted and more easily digestible alternative if you don't want to learn everything in detail.