• Wireless-Extensions--旧的无线驱动框架

• mac80211--为softMAC驱动服务的API

• cfg80211--新的配置API

• nl80211--新的用户控件<->内核空间通讯方式

组件交互的基本原理图
[Wireless Card]
      |
[Linux Kernel ]
  |    |
[udev][libnl]-[iw]      
   |  /   \      
[crda]    \     
    |       \     
[ Wireless ] |
[Regulatory] |
[ Database ] |
             |
             |
        [ hostapd ]
理解每一部分是做什么的
Wireless Card: Should be self explanitory... handles sending/receiving wireless packets
无线网卡：操作接收/发达无线包
Linux Kernel: The linux kernel contains the driver for the wireless card, the mac80211 subsystem which handles packet generation and scheduling, and the nl80211 subsystem, which handles configuring the wireless interfaces for userspace
linux核：linux核包涵了无线网尗的驱动，mac80211子系统处理包的产生与时序安排。nl80211处理在用户空间配置无线接口  cfg80211
libnl: libnl is the transport layer used to communicate with the kernel via netlink
libnl:通过netlink与内核对话的传输层
udev: udev is the facility the kernel uses to pass events/calls to crda
udev:udev是内核通过events/calls到 crda的设施
iw: iw is a userspace utility that we can use to test that libnl is working correctly, as well as create additional virtual wireless interfaces on the wireless card
iw:是我们用来测试libnl是否正确工作，以及在无线网卡上创建额外的虚拟无线接口的用户空间工具。
crda: crda is a userspace program that the kernel queries (through udev) to find what channels/frequencies are usable, and at what powers. This moves the information out of static tables maintained in kernel to userspace, which allows them to be updated without reloading drivers/rebooting
crda:是内核通过udev来查找什么频段／频率是有效的，在什么强度的用户空间程序。这个从内核维护的静态表中移到用户空间，它可以不需要重载驱动和重启的情况下更新。
Wireless Regulatory Database: database of allowable frequencies and transmit power levels used by crda
无线控制数据库：crda使用允许的频率和传输强度等级的数据库
hostapd: This is the daemon that handles generation of beacons and other wireless packets, as wel as wpa-psk, wpa2, etc encryptions.
hostapd:这是个用来操作信号的产生和其它无线包，以及wpa-psk, wpa2等加密的守护进程
softMAC是一个用于描述无线网尗的类型的一个术语。

WEXT/mac80211/nl80211/cfg80211