If you want to get familiar with TCP/UDP and are not gun-shy with C I would suggest the Pocket Socket Guide (now Practical Guide to TCP sockets)[1]. I have a really old edition, but it ages extremely well, and its one of the books I always use to refresh myself on network programming basics.
[1]: https://www.amazon.com/gp/product/0123745403/ref=ox_sc_act_t...