I think there are better (more correctly written) guides to network programming, i.e., UNIX Network Programming (old, but the newest volume: The Sockets Networking API - was written in 2003), and TCP/IP Illustrated (also most recently updated with a 2nd edition in 2011) by the late, great W. Richard Stevens - despite his sole work being horribly out of date, with later volumes being worked on by Bill Fenner and Andy Rudoff, I would honestly look no further in lieu of socket programming in C.