Can't go wireless with an ATHEROS card in Ubuntu

Your English is fine :)

The first thing you should try is putting "sudo" in front of all of your wireless commands:
sudo iwconfig ath0 essid "rbarrca"
sudo iwconfig ath0 ap 00:14:A5:C5:95:13
sudo dhclient ath0

Using sudo will get around the operation-not-permitted errors that you are getting. If you still have problems, post the results from the commands using sudo.

You can read more about sudo here: https://wiki.ubuntu.com/RootSudo

Hello Adam, thanks for your help. I followed the steps and here is the output. I still cannot get connected:

rbarra@Chuqui:~$ wlanconfig ath0 list scan
SSID BSSID CHAN RATE S:N INT CAPS
rbarrca 00:14:a5:c5:95:13 6 54M 70:0 100 EPs

rbarra@Chuqui:~$ iwlist ath0 scan
ath0 Scan completed :
          Cell 01 - Address: 00:14:A5:C5:95:13
                    ESSID:"rbarrca"
                    Mode:Master
                    Frequency:2.437 GHz (Channel 6)
                    Quality=70/70 Signal level=-25 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

rbarra@Chuqui:~$ sudo iwconfig ath0 essid "rbarrca"
[sudo] password for rbarra:
rbarra@Chuqui:~$ sudo iwconfig ath0 ap 00:14:A5:C5:95:13
rbarra@Chuqui:~$ sudo dhclient ath0
There is already a pid file /var/run/dhclient.pid with pid 7510
killed old client process, removed PID file
Internet Systems Consortium DHCP Client V3.0.5
Copyright 2004-2006 Internet Systems Consortium.
All rights reserved.
For info, please visit http://www.isc.org/sw/dhcp/

wifi0: unknown hardware address type 801
wifi0: unknown hardware address type 801
Listening on LPF/ath0/00:1d:d9:41:f8:30
Sending on LPF/ath0/00:1d:d9:41:f8:30
Sending on Socket/fallback
DHCPDISCOVER on ath0 to 255.255.255.255 port 67 interval 4
DHCPDISCOVER on ath0 to 255.255.255.255 port 67 interval 8
DHCPDISCOVER on ath0 to 255.255.255.255 port 67 interval 11
DHCPDISCOVER on ath0 to 255.255.255.255 port 67 interval 8
No DHCPOFFERS received.
No working leases in persistent database - sleeping.
rbarra@Chuqui:~$

In the last step, I should be able to see that the DHCP server allocated some IP address (as stated in http://madwifi.org/wiki/UserDocs/FirstTimeHowTo). After this, I don't know what else to do. The strange thing is that in the Wicd pannel, I can see the net (with a green color, see the picture provided in the first post) but I just can't connect to it. Maybe I am missing some parameters as an IP Address, MAC Address, DNS information, type of encryption, or something like that.

Thanks again!

Some additional info... Here I have two more screenshots showing that Wicd DOES detect my wireless net ("rbarrca"). It even detects another "Untitled" net, which might be my neighbors.

http://rbarra.vtrbandaancha.net/wicd_wireless.png

Then, if I use the Ubuntu Network Manager, I also have the wireless connection enabled, but maybe it's just that I have not configured correctly the Settings in order to get connected.

http://rbarra.vtrbandaancha.net/network_manager.png

Regards!

I did it! I did it! Wow!!

Don't ask me how, but after changing some parameters (almost randomly) in the Wicd preferences for the wireless network, it worked out and now I'm surfing wireless. But I still have some questions...

1. What does the "Connected to rbarraca at XXX (IP: XXX.XX.XXX.XXX)" status message at the bottom of the Wicd Manager mean?

Take a look at http://rbarra.vtrbandaancha.net/connected.png

The fisrt number "XXX" changes all the time... constantly...

2. How do I set it up for Wicd to start automatically every time I turn on the computer?

3. How do I set my wireless connection to start automatically when I turn on the computer?

4. Lastly, is it correct to use WEP instead of WPA?

Thanks!!
8-)

1) The XXX number is the signal strength I believe. Right now mine says "79" which I take to be "79%".
2) Add wicd to your "System|Preferences|Sessions" dialog under "Startup Programs" to make it start with your system.
3) It should start automatically if you have the "Connect Automatically" box checked...It doesn't apparently.
4) WPA is considered "better" than WEP but either one is better than nothing...all that just keeps the honest people honest, I guess. If someone wants it bad enough they'll find a way (or just steal your laptop!)

Hope some of this helps you. If you find out how to make wicd connect automatically, let me know!!

Thanks!!

Thank you very much, Greg. All the information has been useful.

My Wicd connects automatically, just following the steps metioned by you. I hope that's what you asked for.

Best regards.

Invalidating old bug-report-like question.