You've come this far, and now you're screaming for more! Where else can you go to learn more about all this stuff?
Try the following man pages, for starters:
Also, look up the following books:
Internetworking with TCP/IP, volumes I-III by Douglas E. Comer and David L. Stevens. Published by Prentice Hall. Second edition ISBNs: 0-13-468505-9, 0-13-472242-6, 0-13-474222-2. There is a third edition of this set which covers IPv6 and IP over ATM.
Using C on the UNIX System by David A. Curry. Published by O'Reilly & Associates, Inc. ISBN 0-937175-23-4.
TCP/IP Network Administration by Craig Hunt. Published by O'Reilly & Associates, Inc. ISBN 0-937175-82-X.
TCP/IP Illustrated, volumes 1-3 by W. Richard Stevens and Gary R. Wright. Published by Addison Wesley. ISBNs: 0-201-63346-9, 0-201-63354-X, 0-201-63495-3.
Unix Network Programming by W. Richard Stevens. Published by Prentice Hall. ISBN 0-13-949876-1.
On the web:
BSD Sockets: A Quick And Dirty Primer (has other great Unix system programming info, too!)
Intro to TCP/IP (gopher)