If you want to further your understanding of network protocols, there's an excellent open textbook available here: http://cnp3book.info.ucl.ac.be/
At Uni we had a book called "Computer Networking - A top down approach". One of the best teaching books I've ever read. The amount of detail is very nice balanced, and as the title says it's a top down approach where one layer at a time is discussed. Very interesting.
We're using that same book, sixth edition, in my networks course right now. It's overly verbose like every other textbook, but the content is solid.