YDL.net

TOPIC: Wireless Tools

Introduction
There are a few nice command line tools that really help with wireless AP discovery and application, as follows.

Verify that you have wireless-tools installed (is by default in Yellow Dog 5 for Apple) and that it sees the device:

   [root@localhost ~]# iwconfig eth1

   eth1      IEEE 802.11b/g  ESSID:off/any  Nickname:"Broadcom 4306"
             Mode:Managed  Frequency=2.437 GHz  Access Point: Invalid
             Bit Rate:1 Mb/s   Tx-Power=15 dBm
             RTS thr:off   Fragment thr:off
             Encryption key:off
             Link Quality=0/100  Signal level=-256 dBm  Noise level=-256 dBm
             Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
             Tx excessive retries:0  Invalid misc:0   Missed beacon:0

Scan for your wireless AP (if you don't know the settings):

   [root@localhost ~]# iwlist eth1 scanning
   eth1      Scan completed :
             Cell 01 - Address: 00:13:46:EF:8D:64
                       ESSID:"Cercle"
                       Protocol:IEEE 802.11bg
                       Mode:Master
                       Channel:6
                       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
                       Quality=89/100  Signal level=-62 dBm  Noise level=-67 dBm
                       Extra: Last beacon: 52ms ago
             Cell 02 - Address: 00:C0:49:EC:37:40
                       ESSID:"foobar"
                       Protocol:IEEE 802.11bg
                       Mode:Master
                       Channel:8
                       Encryption key:off
                       Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 6 Mb/s; 9 Mb/s
                                 11 Mb/s; 12 Mb/s; 18 Mb/s; 22 Mb/s; 24 Mb/s
                                 36 Mb/s; 48 Mb/s; 54 Mb/s
                       Quality=97/100  Signal level=-44 dBm  Noise level=-67 dBm
                       Extra: Last beacon: 4ms ago

From this output above, my laptop can see two wireless APs. One is mine (foobar) and the other is another one in close proximity. I can now use this to set my wireless setup. From above, I can see that I have encryption off (see another how-to to enable encryption), my AP is channel 8 and the SSID is 'foobar':

[root@localhost ~]# iwconfig eth1 channel 8 txpower on rate auto essid foobar

And now I can get an IP from it via DHCP:

   [root@localhost ~]# dhclient eth1
   Internet Systems Consortium DHCP Client V3.0.3-RedHat Copyright 2004-2005
   Internet Systems Consortium.
   All rights reserved.
   For info, please visit http://www.isc.org/products/DHCP

   Listening on LPF/eth1/00:11:24:a1:a9:4d
   Sending on   LPF/eth1/00:11:24:a1:a9:4d
   Sending on   Socket/fallback
   DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 4
   DHCPOFFER from 192.168.123.254
   DHCPREQUEST on eth1 to 255.255.255.255 port 67
   DHCPACK from 192.168.123.254
   bound to 192.168.123.100 -- renewal in 275368 seconds.

And I can now see that I've been assigned 192.168.123.100 as my IP address. I am now connected and can surf as I please.

This HOWTO was written by Christopher Murtagh, Terra Soft Solutions