-----序言
To do research in the source code of a large project is to enter a strange, new land with its own customs and unspoken expectations. It is useful to learn some of the major conventions up front, and to try interacting with the inhabitants instead of merely standing back and observing.
通过源代码来学习一个系统工程，就像进入一快陌生的新大陆，他拥有自己的风俗和前景。预先熟悉一些常用习俗是有益的。尝试同原住民交流也要好过仅仅站在一旁观察。
The bulk of this chapter is devoted to introducing you to a few of the common programming patterns and tricks that you'll often meet in the networking code.
本章主要介绍一些在网络编程中经常用到的编程模式和技巧
I encourage you, when possible, to try interacting with a given part of the kernel networking code by means of user-space tools. So in this chapter, I'll give you a few pointers as to where you can download those tools if they're not already installed on your preferred Linux distribution, or if you simply want to upgrade them to the latest versions.
我鼓励大家 在适当的时候，尝试通过user_space（命名空间？）工具提供的方法来学习书中给出的核心网络代码。所以如果你还没有在你Linux系统中安装那些工具或希望把已经安装的工具升级到最新版本，本章将会提供大家一些网络站点来供大家下载。
I'll also describe some tools that let you find your way gracefully through the enormous kernel code. Finally, I'll explain briefly why a kernel feature may not be integrated into the official kernel releases, even if it is widely used in the Linux community.
本书还会介绍很多工具，他们能够帮助你顺利的理解庞大的内核代码。最后我会简短的介绍为什么即使某些内核功能被广泛的应用于Linux系统却还是没有被整合入正式发行版本的内核中。