Networking Linux: A Practical Guide to TCP/IP

This is how-to actually implement TCP/IP and services - and calm, step-by-step instructions on debug and troubleshooting specific network problems, which in themselves are invaluable. Especially when you are tearing your hair out and really should be stepping back, taking a calm deep breath and taking it one step at a time... Covers tcp/ip basic protocol and packet information, then specific steps and uses for ping, traceroute, arp, ngrep, ethereal, nessus, mon, iptables (the replacement for ipchains), OPIE, tcpwrappers, more. Very clear, very useful.