You've come this far, and now you're screaming for more! Where else can you go to learn more about all this stuff?
For old-school actual hold-it-in-your-hand pulp paper books, try some of the following excellent guides. Note the prominent Amazon.com logo. What all this shameless commercialism means is that I basically get a kickback (Amazon.com store credit, actually) for selling these books through this guide. So if you're going to order one of these books anyway, why not send me a special thank you by starting your spree from one of the links, below.
Besides, more books for me might ultimately lead to more guides for you. ;-)
Unix Network Programming, volumes 1-2 by W. Richard Stevens. Published by Prentice Hall. ISBNs for volumes 1-2: 013490012X, 0130810819.
Internetworking with TCP/IP, volumes I-III by Douglas E. Comer and David L. Stevens. Published by Prentice Hall. ISBNs for volumes I, II, and III: 0130183806, 0139738436, 0138487146.
TCP/IP Illustrated, volumes 1-3 by W. Richard Stevens and Gary R. Wright. Published by Addison Wesley. ISBNs for volumes 1, 2, and 3: 0201633469, 020163354X, 0201634953.
TCP/IP Network Administration by Craig Hunt. Published by O'Reilly & Associates, Inc. ISBN 1565923227.
Advanced Programming in the UNIX Environment by W. Richard Stevens. Published by Addison Wesley. ISBN 0201563177.
Using C on the UNIX System by David A. Curry. Published by O'Reilly & Associates, Inc. ISBN 0937175234. Out of print.
On the web:
BSD Sockets: A Quick And Dirty Primer (has other great Unix system programming info, too!)
The Unix Socket FAQ
Intro to TCP/IP
Another Different Intro to TCP/IP
The Winsock FAQ
RFCs--the real dirt:
RFC-768--The User Datagram Protocol (UDP)
RFC-791--The Internet Protocol (IP)
RFC-793--The Transmission Control Protocol (TCP)
RFC-854--The Telnet Protocol
RFC-951--The Bootstrap Protocol (BOOTP)
RFC-1350--The Trivial File Transfer Protocol (TFTP)