iwconfig是Linux Wireless Extensions(LWE)的用户层配置工具之一。LWE是Linux下对无线网络配置的工具，包括内核的支持、用户层配置工具和驱动接口的支持三部分。目前很多无线网卡都支持LWE，而且主流的Linux发布版本，比如Redhat Linux、Ubuntu Linux都已经带了这个配置工具。 4

1. 安装 wireless_tools 和 madwifi

pacman -S wireless_tools madwifi

1. 查看网卡状态

   lsusb
   Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
   Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
   Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
   Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
   Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
   Bus 002 Device 002: ID 093a:2510 Pixart Imaging, Inc. Optical Mouse
   Bus 001 Device 003: ID 0cf3:7015 Atheros Communications, Inc.
   

   在USB接口001/003上检测到网卡。 ``` iwconfig lo no wireless extensions.

eth0 no wireless extensions.

wlan0 IEEE 802.11bgn ESSID:off/any
Mode:Managed Access Point: Not-Associated Tx-Power=0 dBm
Retry long limit:7 RTS thr:off Fragment thr:off Encryption key:off Power Management:off ``` 无线网卡为 wlan0

1. 激活网卡

ifconfig wlan0 up

因为我的网卡必需要先激活才能扫描，否则下一步scan会出现错误：wlan0 Interface doesn’t support scanning.

1. 扫描网络

   iwlist wlan0 scan
   wlan0     Scan completed :
          Cell 01 - Address: 54:E6:FC:22:E1:D2
                    Channel:1
                    Frequency:2.412 GHz (Channel 1)
                    Quality=53/70  Signal level=-57 dBm  
                    Encryption key:on
                    ESSID:"TP-LINK_22E1D2"
                    Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 6 Mb/s
                              9 Mb/s; 12 Mb/s; 18 Mb/s
                    Bit Rates:24 Mb/s; 36 Mb/s; 48 Mb/s; 54 Mb/s
                    Mode:Master
                    Extra:tsf=000000292a41bd80
                    Extra: Last beacon: 960ms ago
                    IE: Unknown: 000E54502D4C494E4B5F323245314432
                    IE: Unknown: 010882848B960C121824
                    IE: Unknown: 030101
                    IE: IEEE 802.11i/WPA2 Version 1
                        Group Cipher : CCMP
                        Pairwise Ciphers (1) : CCMP
                        Authentication Suites (1) : PSK
                    IE: WPA Version 1
                        Group Cipher : CCMP
                        Pairwise Ciphers (1) : CCMP
                        Authentication Suites (1) : PSK
   

发现WPA2-PSK/WPA-PSK 加密网络 TP-LINK_22E1D2，因为加密方式为 WPA-PSK 所以得用 wpa_supplicant 而不能使用 iwconfig wlan0 key xxx 形式，iwconfig key方式适用于WEP。

1. 配置 wpa_supplicant

新建文件 /etc/my_wpa_supplicant.conf

ctrl_interface=/var/run/wpa_supplicant
network={
	ssid="TP-LINK_22E1D2"
	psk="密码"
}

因为全部使用默认配置，所以配置文件非常简单。

1. 连接wlan0到网络，并以daemon方式运行 wpa_supplicant -B -i wlan0 -c /etc/my_wpa_supplicant.conf

-B Background 在后台以daemon 运行
-i interface
-c 配置文件

1. 设置IP地址
   ifconfig wlan0 192.168.1.131
   ifconfig 查看状态

   wlan0     Link encap:Ethernet  HWaddr 54:E6:FC:03:0D:6B  
          inet addr:192.168.1.131  Bcast:192.168.1.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:95 errors:0 dropped:0 overruns:0 frame:0
          TX packets:4 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:32434 (31.6 Kb)  TX bytes:576 (576.0 b)
   

2. 加入网关到路由 我的网关的是192.168.1.1，添加通过wlan0访问的网关

   route add default gw 192.168.1.1 dev wlan0
   

   查看状态

   Kernel IP routing table
   Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
   192.168.1.0     *               255.255.255.0   U     0      0        0 wlan0
   default         192.168.1.1     0.0.0.0         UG    0      0        0 wlan0
   

3. 设置完毕。 以后上线只需运行以下命令即可

   wpa_supplicant -B -i wlan0 -c /etc/my_wpa_supplicant.conf
   ifconfig wlan0 192.168.1.131
   route add default gw 192.168.1.1 dev wlan0
   

4. 相关命令 关闭连接 wpa_cli terminate 连接状态 wpa_cli status