While some of the technical choices made during its design have no doubt played a role, the single most important factor in the overwhelming success of transmission control protocol/Internet protocol (TCP/IP) is arguably the openness of both the design process itself and the resulting standards. Likewise, the openness of GNU/Linux has made it the platform of choice for developers and researchers experimenting with TCP/IP and internetworking applications.

While availability of the source and the freedom to modify it is essential, a daunting barrier to real access for any developer or researcher is the magnitude of the initial effort required to understand the design and source code for such a complex subsystem of the Linux kernel. Faced with precisely this problem when delving into the code, Seth and Venkatesulu invested immense energy in producing an invaluable detailed reference book that can light the way for all who desire to work with the TCP/IP stack. The authors rightly identify developers who are making server-side or embedded-system products for corporations, entrepreneurs, and security-conscious defense organizations as the main target audience. They also position this book as a useful resource for researchers, academia, and the open-source community.

The book is very well organized. Included in the preliminaries are the kernel interfaces and the protocol concepts. This is followed by a detailed treatment of sockets and connection setup by application programs. The structure of a network packet and how it traverses the layers--in both directions--is covered next. This is followed by an extensive treatment of TCP state machine and the implementation of various timers and memory management. A comprehensive look at the IP layer follows, with chapters on routing, quality of service, and security features in the netfilter framework. The book concludes with chapters on the link layer and tools useful for debugging. In a final separate chapter on the next edition, the authors give tantalizing teasers on the additional topics to be included, such as user datagram protocol (UDP), multicasting and broadcasting, and IPv6.

From a descriptive point of view, the book’s style is impeccable. The excellent diagrams are carefully designed and included to explain both the control flow and the data structures involved in every complex algorithm. Relevant excerpts from the actual code are also included in the right places. This will be of immense value to any developer who wishes to understand and modify the code.

To increase the value of this book to researchers and students, the authors should include some treatment, even a brief one, from two other perspectives. The first would be to give some context of the history and evolution of the code; this would help readers gain some understanding of the various design choices that are considered and why the code is currently the way it is. The second would be an analytical evaluation of the design, touching on issues such as performance and security; this could lead to interesting suggestions for both short- and long-term projects.