3.打开无线网卡电源
$ sudo iwconfig eth0 txpower on
4.检索区域内的无线网络
$ iwlist eth0 scan
eth0 Scan completed :
Cell 01 - Address: 00:1D:0F:4D:8B:E4
ESSID:"TP-LINK"
Mode:Master
Frequency:2.437 GHz (Channel 6)
Quality=28/70 Signal level=-67 dBm Noise level=-95 dBm
Encryption key:off
Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 6 Mb/s
12 Mb/s; 24 Mb/s; 36 Mb/s; 9 Mb/s; 18 Mb/s
48 Mb/s; 54 Mb/s
Extra:bcn_int=100
Extra:ath_ie=dd0900037f01010008ff7f
Cell 02 - Address: 00:21:27:3A:37:0A
ESSID:"TP-LINK"
Mode:Master
Frequency:2.437 GHz (Channel 6)
Quality=12/70 Signal level=-83 dBm Noise level=-95 dBm
Encryption key:on
Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 6 Mb/s
12 Mb/s; 24 Mb/s; 36 Mb/s; 9 Mb/s; 18 Mb/s
48 Mb/s; 54 Mb/s
Extra:bcn_int=100
Extra:ath_ie=dd0900037f01010008ff7f
Cell 03 - Address: 00:18:39:A6:98:E2
ESSID:"linksys"
Mode:Master
Frequency:2.437 GHz (Channel 6)
Quality=3/70 Signal level=-92 dBm Noise level=-95 dBm
Encryption key:on
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; 24 Mb/s; 36 Mb/s
48 Mb/s; 54 Mb/s
Extra:bcn_int=100
IE: WPA Version 1
Group Cipher : CCMP
Pairwise Ciphers (1) : CCMP
Authentication Suites (1) : PSK
我附近有三个无线AP，ESSID所标记的就是无线AP的名字了，其中有两个无线AP都叫做 TP-LINK，另一个叫
linksys，记下这几个无线AP的名字，一会得挨个试。
5.连接无线AP
$ sudo iwconfig ath0 essid "linksys"
$ ifconfig
不管连上还是连不上都不会给出任何提示，到底连没连上还需要使用命令查看一下才行
$ iwconfig eth0
eth0 IEEE 802.11g ESSID:"linksys" Nickname:""
Mode:Managed Frequency:2.462 GHz Access Point: Not-Associated
Bit Rate:0 kb/s Tx-Power:18 dBm Sensitivity=1/1
Retry:off RTS thr:off Fragment thr:off
Power Management:off
Link Quality=0/70 Signal level=-95 dBm Noise level=-95 dBm
Rx invalid nwid:8172 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0
上面的黑体字的部分说明没有连接成功，没关系再换一个就是了。
$ sudo iwconfig eth0 essid "TP-LINK"
$ ifconfig
执行后再查看一下接入状态
$ iwconfig eth0
eth0 IEEE 802.11g ESSID:"TP-LINK" Nickname:""
Mode:Managed Frequency:2.437 GHz Access Point: 00:1D:0F:4D:8B:E4
Bit Rate:36 Mb/s Tx-Power:18 dBm Sensitivity=1/1
Retry:off RTS thr:off Fragment thr:off
Power Management:off
Link Quality=26/70 Signal level=-69 dBm Noise level=-95 dBm
Rx invalid nwid:8268 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0
ok，总算是连上了。
注意：如果连接AP需要密码，而你确实也知道AP的密码，那么可以用下面的办法连接
假设密码是 123456789，密码需要四位一组用”-“分开。
$ sudo iwconfig ath0 essid "TP-LINK" key 1234-5678-9
6.启用无线网卡
$ sudo ifconfig ath0 up
7.设置无线网卡采用dhcp方式自动获取ip
$ sudo dhclient ath0
Internet Systems Consortium DHCP Client V3.0.6
Copyright 2004-2007 Internet Systems Consortium.
All rights reserved.
wifi0: unknown hardware address type 801
wifi0: unknown hardware address type 801
Listening on LPF/ath0/00:19:e0:85:73:70
Sending on LPF/ath0/00:19:e0:85:73:70
Sending on Socket/fallback
DHCPDISCOVER on ath0 to 255.255.255.255 port 67 interval 6
DHCPOFFER of 192.168.1.104 from 192.168.1.1
DHCPREQUEST of 192.168.1.104 on ath0 to 255.255.255.255 port 67
DHCPACK of 192.168.1.104 from 192.168.1.1
bound to 192.168.1.104 -- renewal in 3125 seconds.
现在就可以拔掉网线，使用无线网卡上网了。
8.断开网络
如果需要断开网络，可以使用下面的命令
$ sudo ifconfig ath0 down