1.什么是wpa_spplicant
wpa_supplicant本是开源项目源码,被谷歌修改后加入android移动平台,它主要是用来支持WEP,WPA/WPA2和WAPI无线协议和加密认证的,而实际上的工作内容是通过socket(不管是wpa_supplicant与上层还是wpa_supplicant与驱动都采用socket通讯)与驱动交互上报数据给用户,而用户可以通过socket发送命令给wpa_supplicant调动驱动来对WiFi芯片操作。 简单的说,wpa_supplicant就是WiFi驱动和用户的中转站外加对协议和加密认证的支持。
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"
}