This is a book published by Wiley. It is the first cut at trying to document how the Linux kernel implementaitons work. Most of it is source code from around the Linux 2.4.0 time.
TCP IP 4 Linux draft
Gerald Maguire at KTH provided a LOT of errata~!!! so many thanks to him. We are working on a new edition, given Wiley let us, which will fix these and add material (hopefully some from colleagues at UCL and Loughborough!).