IMHO,

If you're anything like me, download and install Wireshark. This lets you see exactly what goes on. The book will probably make much more sense when you've seen things with your own eyes. Learn to recognize the handshakes, understand why they work that way and what can go wrong. Get a firm understanding of ports and sessions, then you'll see why the rest of the TCP/IP book is probably of little use to you as an app/script developer.

A racecar driver only needs to know so much about how roads are constructed.