Configuring Wireless on Ubuntu Linux (6.06 Dapper Drake)

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I use Ubuntu Dapper Drake as my main operating system. Sometimes I have difficulty connecting to wireless connections. I am writing this post to share what I have learned about using wireless Internet on Ubuntu.

My computer is an Lenovo (IBM) ThinkPad T43 with Centrino. I can usually just turn on the computer and be connected to a wireless signal. At other times, it requires some tinkering, and in the worst (rare) cases, it does not connect at all. But by following these steps, you should be able to troubleshoot most wireless connection problems in Ubuntu.

I am writing this post from the Fort Lauderdale International Airport in Florida, where there is an obvious wireless Internet signal. My laptop is connected to the signal, but cannot connect to the Internet.

The GNOME Network Connection Properties Tool

Below is a screenshot of my current Connection Properties. You can find this tool in the upper right corner of your Ubuntu GNOME desktop.

Ubuntu Connection Properties dialog

It shows that the signal strength is 96%. I clicked on the Configure button to get to the next screen shown below:

GNOME Network Settings

I double-clicked on the eth1 interface (my wireless card), and got to the next screen. I changed the Network Name (ESSID) by clicking next to the input box.

Interface properties

After clicking the "OK" buttons, I still couldn't connect. I typed iwlist eth1 scanning in the terminal to see a list of all wireless signals in the area as shown below:

iwlist eth1 scanning

That didn't provide any additional information. I also tried the command iwconfig, which shows more information about a wireless connection.

iwconfig Ubuntu Linux

Finally, I went back into the Network Connection Properties tool and clicked on the DNS tab. I saw that my previous t-mobile connection from earlier in the day was listed in my Search Domains box, as shown by the red arrow below. As soon as I deleted that, I was able to connect to the wireless Internet signal.

Search settings

Other Possible Ubuntu Linux Wireless Problems

Sometimes I find that I have to deactivate the wireless interface, click all of the "OK" buttons, and then re-enable it before it will work. I'm not sure why.

If you have installed a firewall, it may be interfering with your wireless connection. If you can't seem to connect no matter what you do, try disabling the software firewall.

If all else fails, set up the connection settings the way that you think they are supposed to be. Then reboot the computer. Sometimes that works.

Wireless Internet from the Linux Terminal

iwconfig
Typing iwconfig in a terminal gives you information about your wireless connection. You can also change the settings of your wireless connection with iwconfig. Type man iwconfig in a terminal for more information.
iwlist
Gets detailed information about a wireless interface. On my laptops, the wireless interface is usually eth1, although if I add an additional wireless card, the second one will show up as eth2. I use the iwlist command to scan for wireless networks like this: iwlist eth1 scanning. Type man iwlist in a terminal to learn more about how to use it.

There are several other command line tools that relate to wireless networking, but they don't really apply here. More information about them can be found in the man pages for iwconfig.

Other Linux Wireless Tips

If you have any information to add to what I've written here, please leave a comment.


Comments

wireless internet problem

Hi,
I have installed ubuntu 8.1 on a flash 8Gb stick so that I can travel anywhere with all my documents and OS.
I have connected Alfa network wireless usb device to my pc and got connected to the access point, but when I open firefox and try www.google.com to brows or may other web page, I get an error / warning “Address Not Fount”, when I type google.com –c 4 on the terminal as root, I am getting the following message “ping: unknown host google.com”

Appreciate your support and immediate response.

please find below logs

root@r-nav:/etc/network# iwconfig

wlan1

IEEE 802.11bg ESSID:”Abc”
Mode:Managed Frequency:2.462 GHz Access Point:

00:1B:9E:BE:AA:03
Bit Rate=54 Mb/s Tx-Power=27 dBm
Retry min

limit:7 RTS thr:off Fragment thr=2352 B
Encryption key:off
Power

Management:off
Link Quality=54/100 Signal level:65/65
Rx invalid

nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid

misc:0 Missed beacon:0

---------------------------------------------------
root@r-nav:/etc/network# ping google.com -c 4

ping: unknown host google.com

-------------------------------------------------------

root@r-nav:/tmp/rtl8187b# dhclient
Internet Systems Consortium DHCP Client V3.1.1
Copyright 2004-2008 Internet Systems Consortium.
All rights reserved.
For info, please visit http://www.isc.org/sw/dhcp/

wmaster0: unknown hardware address type 801
wmaster0: unknown hardware address type 801
Listening on LPF/pan0/8e:a0:33:b0:48:cb
Sending on LPF/pan0/8e:a0:33:b0:48:cb
Listening on LPF/wmaster0/
Sending on LPF/wmaster0/
Listening on LPF/eth1/00:17:31:1c:23:0e
Sending on LPF/eth1/00:17:31:1c:23:0e
Listening on LPF/wlan1/00:c0:ca:1b:d3:d5
Sending on LPF/wlan1/00:c0:ca:1b:d3:d5
Listening on LPF/eth0/00:17:31:1c:29:4d
Sending on LPF/eth0/00:17:31:1c:29:4d
Sending on Socket/fallback
DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 3
DHCPDISCOVER on pan0 to 255.255.255.255 port 67 interval 3
DHCPDISCOVER on wmaster0 to 255.255.255.255 port 67 interval 7
DHCPDISCOVER on wlan1 to 255.255.255.255 port 67 interval 3
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 10
DHCPDISCOVER on wlan1 to 255.255.255.255 port 67 interval 9
DHCPDISCOVER on wmaster0 to 255.255.255.255 port 67 interval 8
DHCPDISCOVER on pan0 to 255.255.255.255 port 67 interval 7
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 9
DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 5
No DHCPOFFERS received.
No working leases in persistent database - sleeping.

Webmaster Tips's picture

ubuntu wireless

I'm not sure what the issue is in your case. I recommend asking in the Ubuntu forums or on IRC chat channel #ubuntu. There is probably someone there who knows the answer.

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