WiFi

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Revision as of 17:45, 14 January 2010 by JulienB (Talk | contribs) (Connect to an unencrypted AP)

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Note Note: To configure WiFi you need to install wireless tools first and of course to have a running WiFi interface like: the APF27 wireless extension board or a USB to WiFi adapter, with corresponding Linux drivers loaded.


Common operations

List network interfaces supporting WiFi

 # iwconfig
 lo        no wireless extensions.
 
 eth0      no wireless extensions.
 
 sit0      no wireless extensions.
 
 wmaster0  no wireless extensions.
 
 wlan0     IEEE 802.11bg  ESSID:""  
           Mode:Managed  Frequency:2.412 GHz  Access Point: Not-Associated   
           Tx-Power=0 dBm   
           Retry min limit:7   RTS thr:off   Fragment thr=2352 B   
           Encryption key:off
           Power Management:off
           Link Quality:0/100  Signal level:112/146  Noise level:0/0
           Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
           Tx excessive retries:0  Invalid misc:0   Missed beacon:0

Show all Access Points (AP) available for your APF (here with wlan0 interface)

# iwlist wlan0 scan

wlan0     Scan completed :
          Cell 01 - Address: XX:XX:XX:66:47:48
                    ESSID:"TOTO"
                    Mode:Master
                    Channel:1
                    Frequency:2.412 GHz (Channel 1)
                    Quality=88/100  Signal level:25/100
                    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:tsf=00000009d398fec8
                    Extra: Last beacon: 1390ms ago
...

Connect to an unencrypted AP

# iwconfig wlan0 essid AP_NAME
  • Check it:
# iwconfig wlan0

Get an IP address

# udhcpc -i wlan0


Encryption settings

To configure WiFi cryptography, only WEP can be set as is. If you want to configure dongle for WPA, install wpa_supplicant.

WEP configuration

This example is given for a WiFi Access Point named armadeus, but the key is false of course ;) :

 # iwconfig wlan0 essid armadeus
 # iwconfig wlan0 key 12345678901234567890
 # ifconfig wlan0 up
 firmware: requesting rt73.bin
 ADDRCONF(NETDEV_UP): wlan0: link is not ready
 # ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready

Now, the WiFi adapter is ready and attached :

 # iwconfig
 lo        no wireless extensions.
 
 eth0      no wireless extensions.
 
 sit0      no wireless extensions.
 
 wmaster0  no wireless extensions.
 
 wlan0     IEEE 802.11bg  ESSID:"armadeus"  
           Mode:Managed  Frequency:2.437 GHz  Access Point: 00:1B:2F:E7:E4:08   
           Bit Rate=2 Mb/s   Tx-Power=7 dBm   
           Retry min limit:7   RTS thr:off   Fragment thr=2352 B   
           Encryption key:XXXXXXXXXXXXXXXXXXXXXXXXXX   Security mode:restricted
           Power Management:off
           Link Quality:0/100  Signal level:73/146  Noise level:0/0
           Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
           Tx excessive retries:0  Invalid misc:0   Missed beacon:0
 

We can configure the network to access internet via the WiFi interface instead of the Ethernet one :

 # ifconfig eth0 down
 # ifconfig wlan0 192.168.0.212
 # route add default gw 192.168.0.1 dev wlan0

And configure the nameserver in /etc/resolv.conf

 domain dev.null
 nameserver 192.168.0.207
 ~                   
 ~
 ~

We can now ping the best website in the world :

 # ping www.armadeus.org
 PING www.armadeus.org (213.186.33.5): 56 data bytes
 64 bytes from 213.186.33.5: seq=0 ttl=122 time=66.735 ms
 64 bytes from 213.186.33.5: seq=1 ttl=122 time=50.392 ms
 ^C
 --- www.armadeus.org ping statistics ---
 2 packets transmitted, 2 packets received, 0% packet loss
 round-trip min/avg/max = 50.392/58.563/66.735 ms

Surf on the net

To surf on the web, you can use (for example) links software :

 # links www.armadeus.org

It's an ASCII internet browser. For more informations about Links.

Links