wpa_supplicant无线网络配置

    目前可以使用wireless-tools 或wpa_supplicant工具来配置无线网络。请记住重要的一点是，对无线网络的配置是全局性的，而非针对具体的接口。

   wpa_supplicant是一个较好的选择，但缺点是它不支持所有的驱动。请浏览wpa_supplicant网站获得它所支持的驱动列表。另外，wpa_supplicant目前只能连接到那些你已经配置好ESSID的无线网络。wireless-tools支持几乎所有的无线网卡和驱动，但它不能连接到那些只支持WPA的AP。
    经过编译后的wpa_supplicant源程序可以看到两个主要的可执行工具：wpa_supplicant和wpa_cli。wpa_supplicant是核心程序，它和wpa_cli的关系就是服务和客户端的关系：后台运行wpa_supplicant，使用wpa_cli来搜索、设置、和连接网络。
       如何用wpa_supplicant使能一个wifi连接？
Step by step：
1、运行wpa_supplicant程序；

执行：/system/bin/wpa_supplicant -d -Dwext -iwlan0 -c/data/misc/wifi/wpa_supplicant.conf
其中：
-d ：增加调试信息
-Dwext ：wext，驱动名称
-iwlan0 ：wlan0，网络接口名称
/system/bin/wpa_supplicant ：wpa_supplicant可执行程序path
/data/misc/wifi/wpa_supplicant.conf ：wpa_supplicant的配置文件path
2、运行命令行工具wpa_cli ；
执行 ：wpa_cli -iwlan0 -p/data/system/wpa_supplicant
注，-p/data/system/wpa_supplicant中的wpa_supplicant并不是可执行程序，而是个控制套接字。
此时会进入交互模式。其中交互模式的命令如下表：

Full command	Short command	Description
status	stat	displays the current connection status
disconnect	disc	prevents wpa_supplicant from connecting to any access point
quit	q	exits wpa_cli
terminate	term	kills wpa_supplicant
reconfigure	recon	reloads wpa_supplicant with the configuration file supplied (-c parameter)
scan	scan	scans for available access points (only scans it, doesn't display anything)
scan_result	scan_r	displays the results of the last scan
list_networks	list_n	displays a list of configured networks and their status (active or not, enabled or disabled)
select_network	select_n	select a network among those defined to initiate a connection (ie select_network 0)
enable_network	enable_n	makes a configured network available for selection (ie enable_network 0)
disable_network	disable_n	makes a configured network unavailable for selection (ie disable_network 0)
remove_network	remove_n	removes a network and its configuration from the list (ie remove_network 0)
add_network	add_n	adds a new network to the list. Its id will be created automatically
set_network	set_n	shows a very short list of available options to configure a network when supplied with no parameters. See next section for a list of extremely useful parameters to be used with set_network and get_network.
get_network	get_n	displays the required parameter for the specified network. See next section for a list of parameters
save_config	save_c	saves the configuration

设置网络的基本格式：set_network
<network id> <key> <parameter> [<parameter>]
显示网络信息的基本格式：get_network <network id> <key>
相应的参数如下表：

Key	Description	Parameters
ssid	Access point name	string
id_str	String identifying the network	string
priority	Connection priority over other APs	number (0 being the default low priority)
bssid	Mac address of the access point	mac address
scan_ssid	Enable/disbale ssid scan	0, 1, 2
key_mgmt	Type of key management	WPA-PSK, WPA_EAP, None
pairwise	Pairwise ciphers for WPA	CCMP, TKIP
group=TKIP	Group ciphers for WPA	CCMP, TKIP, WEP104, WEP40
psk	Pre-Shared Key (clear or encrypted)	string
wep_key0	WEP key (up to 4: wep_key[0123])	string
eap	Extensible Authentication Protocol	MD5, MSCHAPV2, OTP, GTC, TLS, PEAP, TTLS
identity	EAP identity string	string
password	EAP password	string
ca_cert	Pathname to CA certificate file	/full/path/to/certificate
client_cert	Pathname to client certificate	/full/path/to/certificate (PEM/DER)
private_key	Pathname to a client private key file	/full/path/to/private_key (PEM/DER/PFX)

eg.1、连接无加密的AP
>add_network  (It will display a network id for you, assume it returns 0)
>set_network 0 ssid
"666"
>set_network 0 key_mgmt
NONE
>enable_network
0
>quit
eg.2、连接WEP加密AP
>add_network   (assume
return 1)
>set_network 1 ssid
"666"
>set_network 1 key_mgmt
NONE
>set_network 1 wep_key0
"your ap password"
>enable_network
1
eg.3、连接WPA-PSK/WPA2-PSK加密的AP
>add_network   (assume
return 2)
>set_network 2 ssid
"666"
>set_network 2 psk
"your pre-shared key"
>enable_network 2
到此，wifi模块就能连接上AP了。
3、以上是通过命令行工具wpa_cli来实现wifi网络的连接。当然，也可以通过wpa_supplicant的配置文件来实现连接。
再回顾下运行wpa_supplicant时执行的命令：
/system/bin/wpa_supplicant -d -Dwext -iwlan0 -c/data/misc/wifi/wpa_supplicant.conf
我们在执行时加上了-c/data/misc/wifi/wpa_supplicant.conf，我们可以将我们要连接的AP的设置以一定的格式写入wpa_supplicant.conf配置文件中即可。
eg. 
ctrl_interface=DIR=/data/system/wpa_supplicant GROUP=system
update_config=1
network={
ssid="my access
point"
proto=WPA
key_mgmt=WPA-PSK
psk="you
pass words"
}
具体格式可参考：http://hostap.epitest.fi/gitweb/gitweb.cgi?p=hostap.git;a=blob_plain;f=wpa_supplicant/wpa_supplicant.conf