| Chapter 1 will deal intensively with the motivation behind Linux in general and the Linux network architecture in particular; Chapter 2 is an introduction into the basic mechanisms and components of the Linux kernel. To keep the volume of this book manageable, we will discuss only those components that are important for understanding the Linux network architecture. With regard to the other components of the Linux kernel, we refer our readers to other books (e.g., [BBDK+01]). Chapter 3 is an introduction to the general architecture of communication systems and the functionality of protocols and protocol instances. It includes an introduction to the popular TCP/IP and ISO/OSI layering models. Chapters 4 and 5 discuss fundamental concepts of the Linux network architecture, including the representation and management of network packets in the Linux kernel (see Socket Buffers?A HREF="0131777203_ch04.html#ch04">Chapter 4) and the concept of network devices (Chapter 5). Network devices form the links between the protocol instances on the higher layers and hide the particularities of the respective network adapters behind a uniform interface. Chapter 6 gives an overview of the activity forms in the Linux network architecture and the flow of transmit and receive processes. In addition, this chapter introduces the interface to the higher-layer protocol instances. Chapters 7 through 12 discuss protocols and mechanisms of the data link layer. More specifically, it describes the SLIP, PPP, and PPP-over-Ethernet protocols and how the ATM and Bluetooth network technologies are supported in Linux. Finally, we will describe how a Linux computer can be used as a transparent bridge. Our discussion of the TCP/IP protocols starts with an overview of the TCP/IP protocol family in Chapter 13. We will begin with a brief history of the Internet, then give an overview of the different protocols within the TCP/IP protocol family. Chapter 14 will deal with the Internet Protocol and its mechanisms in detail. In addition, it introduces the IP options and the ICMP protocol. Chapters 15 through 23 discuss the following protocols and mechanisms on the network layer: ARP, routing, multicasting, traffic control, firewalls, connection tracking, NAT, KIDS, and IPv6. Chapters 24 and 25 describe the TCP and UDP transport protocols, respectively. We will close our discussion of the kernel with an explanation of the socket interface, in Chapter 26, then end with a short overview of the programming of network functionality on the application level. The appendix includes additional information and introduces tools facilitating your work with the Linux network architecture. The issues dealt with include the LXR source code browser, debugging work in the Linux kernel, and tools you can use to manage and monitor the Linux network architecture. | 