computer/network security is such a broad issue, theres no one site or one book that will tell you everything you need to know. I would suggest with the TCP/IP stack, get TCP/IP illustrated by W. rich stevens. After that i would suggest start reading o/s manuals, learn all that you can about wide used o/s 's like linux (red hat, slackware, debian), unix (solaris, freeBSD, openBSD) windows (win2k,NT,XP) and then after that I think you should have a good understanding of what type of reading material you need. Hope this helped, take it easy.
