This is a first effort at collecting information about network programming structs and APIs available in UNIX. I plan on updating this as I find more.
- Linux Journal: Linux Network Programming, Part I, II, III.
- Linux Journal: Multicast Routing Code in the Linux Kernel
- Linux Journal: Inside the Linux Packet Filter, Part I, II
There are of course, in addition to these fine sources, the entire catalogue of work by Richard M. Stevens. May he rest in peace. His works are considered the reference litterature on this subject, see for instance the UNIX Network Programming (review).