Roll your own
Intranet
Learn about TCP, IP, ICMP, UDP, Ethernet and others at the byte level, not
at just the WinSock level. See the actual bytes which flash across the lines
when you use the Internet. This may not be as practical as using the WinSock,
but it's just about as deep as you can dig into the innards of the Internet.
A must read for any serious Internet enthusiast.