Complete and detailed book, with practical examples almost everywhere, and a particular emphasis is put on the TCP/IP internet protocol suite.
But not very nice editing and layout, and a bit confusing at some points.
Around the first 85 pages are dedicated to UNIX in general (signals, daemons, filesystem general structure), and not dedicated to networking.
But it talks about the UNIX techniques you will need in the rest of the book, so you won't really need any other and no assumptions about your networking knowledge are done.
The real book starts providing a detailed description of IPC techniques: pipes, FIFOs, streams, message queues, semaphores, shared memory. It might result confusing when to use each technique and how to combine them.
But each of them comes with comprehensive client-server examples and several file locking implementations that help to fully understand the text, and comparisions and valuable advices.
A few tables are outdated now.
But this is no problem as they are available in your UNIX kernel configuration or include files, and the book shows how to find the right values in each case.
A chapter is dedicated to explain networking terms and concepts (OSI models, byte ordering, buffering, multiplexing, routing..)
But even if it's more than enough to understand how everything presented in the book works, in my opinion its a bit short.
Several protocol suites are described (TCP/IP, XNS, SNA, NetBIOS, OSI, UUCP) so it might be hard to choose the right one for your application.
But the different characteristics and services they provide are compared making this choice easier.
Stevens makes a thorough description of the Berkeley Socket Interface and the System V TLI communication protocol APIs, providing examples and useful routines like the implementation of a reliable UDP/IDP protocol that is later used in some of the project examples in the last part of the book (tftp, lpd, rmt, rlogind, ...), each of them explained in detail.
But for some people this might be too much C source code (around 15000 lines, claims the author), and not enough real life problems or advices. A matter of taste.
There is a part dedicated to security, which explains the Kerberos authentication system and the standard .rhosts, which is applied to the rlogind example.
But the Kerberos chapter along with the one dedicated to the Apollo, Xerox Courier and Sun RPCs, even if they provide enough descriptions and examples, seem to be a bit too short.
In general, I'd say it's a complete book about network programming under UNIX which provides in-depth explanations of the main communication protocols and techniques. And since communication is often a must under UNIX, a very useful book to have near your keyboard.
No buts here, get it :)