Ubuntu 12.04 cannot bring up wlan0

[quan1992]

When I run command "sudo ifconfig wlan0 up", this shows up:
SIOCSIFFLAGS: Device or resource busy

This is what in /etc/network/interfaces:

auto lo
iface lo inet loopback
-----------------------------------------------------------------------------------------------
These are some output related to wlan0:

adrian@ubuntu:~$ iwlist scan
lo Interface doesn't support scanning.
wmx0 Interface doesn't support scanning.
wlan0 Failed to read scan data : Network is down
eth0 Interface doesn't support scanning.

adrian@ubuntu:~$ sudo lshw -C network
[sudo] password for adrian:
*-network
description: Ethernet interface
product: 82579LM Gigabit Network Connection
vendor: Intel Corporation
physical id: 19
bus info: pci@0000:00:19.0
logical name: eth0
version: 04
serial: f0:de:f1:dc:ad:70
size: 1Gbit/s
capacity: 1Gbit/s
width: 32 bits
clock: 33MHz
capabilities: pm msi bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
configuration: autonegotiation=on broadcast=yes driver=e1000e driverversion=1.5.1-k duplex=full firmware=0.13-3 ip=130.215.23.104 latency=0 link=yes multicast=yes port=twisted pair speed=1Gbit/s
resources: irq:50 memory:f4a00000-f4a1ffff memory:f4a2b000-f4a2bfff ioport:6080(size=32)
*-network DISABLED
description: Wireless interface
product: Centrino Advanced-N + WiMAX 6250
vendor: Intel Corporation
physical id: 0
bus info: pci@0000:03:00.0
logical name: wlan0
version: 5e
serial: 64:80:99:3a:83:40
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
configuration: broadcast=yes driver=iwlwifi driverversion=3.2.0-29-generic-pae firmware=41.28.5.1 build 33926 latency=0 link=no multicast=yes wireless=IEEE 802.11abgn
resources: irq:52 memory:f4900000-f4901fff
*-network
description: Ethernet interface
physical id: 2
bus info: usb@2:1.3
logical name: wmx0
serial: 00:1d:e1:49:a9:1d
capabilities: ethernet physical
configuration: driver=i2400m firmware=i6050-fw-usb-1.5.sbcf link=no

adrian@ubuntu:~$ rfkill list all
0: hci0: Bluetooth
Soft blocked: no
Hard blocked: no
1: tpacpi_bluetooth_sw: Bluetooth
Soft blocked: no
Hard blocked: no
2: i2400m-usb:2-1.3:1.0: WiMAX
Soft blocked: no
Hard blocked: no
3: phy0: Wireless LAN
Soft blocked: no
Hard blocked: no

adrian@ubuntu:~$ dmesg | grep iwl
[ 5.522710] iwlwifi 0000:03:00.0: PCI INT A -> GSI 17 (level, low) -> IRQ 17
[ 5.522741] iwlwifi 0000:03:00.0: setting latency timer to 64
[ 5.522783] iwlwifi 0000:03:00.0: pci_resource_len = 0x00002000
[ 5.522785] iwlwifi 0000:03:00.0: pci_resource_base = f8540000
[ 5.522787] iwlwifi 0000:03:00.0: HW Revision ID = 0x5E
[ 5.523266] iwlwifi 0000:03:00.0: irq 53 for MSI/MSI-X
[ 5.523399] iwlwifi 0000:03:00.0: Detected Intel(R) Centrino(R) Advanced-N + WiMAX 6250 AGN, REV=0x84
[ 5.523530] iwlwifi 0000:03:00.0: L1 Enabled; Disabling L0S
[ 5.534106] iwlwifi 0000:03:00.0: device EEPROM VER=0x540, CALIB=0x6
[ 5.534109] iwlwifi 0000:03:00.0: Device SKU: 0X1f0
[ 5.536337] iwlwifi 0000:03:00.0: Tunable channels: 13 802.11bg, 24 802.11a channels
[ 5.585176] iwlwifi 0000:03:00.0: loaded firmware version 41.28.5.1 build 33926
[ 5.587817] ieee80211 phy0: Selected rate control algorithm 'iwl-agn-rs'
[ 6.344593] iwlwifi 0000:03:00.0: L1 Enabled; Disabling L0S
[ 6.344783] iwlwifi 0000:03:00.0: Radio type=0x1-0x2-0x0
[ 6.589745] iwlwifi 0000:03:00.0: L1 Enabled; Disabling L0S
[ 6.589923] iwlwifi 0000:03:00.0: Radio type=0x1-0x2-0x0
-----------------------------------------------------------------------------------------------------------------------
Can anyone help me to solve this problem?
Thanks in advance!

[chili555]

May we see:

rfkill list all

Thanks.

[quan1992]

May we see:

rfkill list all

Thanks.

Hi, chili555, I updated the question. Thanks for your reply!!!

[chili555]

If it's not the wireless switch, we wonder why the wireless is disabled:

*-network DISABLED
description: Wireless interface
product: Centrino Advanced-N + WiMAX 6250
vendor: Intel Corporation
physical id: 0
bus info: pci@0000:03:00.0
logical name: wlan0

Network Manager is designed to disallow wireless if you have wired, and you do. Please temporarily detach the ethernet and then run and post:

dmesg | grep iwl

Thanks.

[quan1992]

Hi, I updated the output of dmesg | grep iwl

I found that I can connect with infrastructure, but I cannot connect with ad-hoc wireless.

[chili555]

I found that I can connect with infrastructure, but I cannot connect with ad-hoc wireless.

'Infrastructure' is for computer-to-router or other access point. 'Ad hoc' is for computer-to-computer. Isn't Infrastructure what you want? Aren't you trying to connect to a router and through it, to the internet?

[quan1992]

'Infrastructure' is for computer-to-router or other access point. 'Ad hoc' is for computer-to-computer. Isn't Infrastructure what you want? Aren't you trying to connect to a router and through it, to the internet?

For some reason, my single board computer can only create ad-hoc wirelss right now. So I want my laptop to connect to this ad-hoc network. Does driver of Ubuntu12.04 has the ability to connect to ad-hoc network? My friends computer running on Ubuntu11.04 can connect to it.

[chili555]

Does driver of Ubuntu12.04 has the ability to connect to ad-hoc network?

Usually, yes. Edit connections in Network Manager and select Ad Hoc. You'll need to specify the BSSID of the station you are connecting to.

[quan1992]

Usually, yes. Edit connections in Network Manager and select Ad Hoc. You'll need to specify the BSSID of the station you are connecting to.

Is BSSID the MAC address of the single board computer showed by "iwconfig"? I tried to select Ad Hoc in network connections and type the MAC address of wlan1 of single board computer. Unfortunately, it still doesn't work.

I noticed that before I try to connect to ad-hoc created by single board computer, I can see wlan0 by typing "ifconfig". But after I try to connect to ad-hoc(doesn't succeed), wlan0 simply disappear in output of "ifconfig".

Do you know why that happened?

[chili555]

Is BSSID the MAC address of the single board computer showed by "iwconfig"?

BSSID is the station name. If, from your laptop, you scan:

sudo iwlist wlan0 scan

Do you see the single-board advertising its network?

Cell 02 - Address: 8x:1B:5E:42:75:xx
Channel:6
Frequency:2.437 GHz (Channel 6)
Quality=23/70 Signal level=-87 dBm
Encryption key:on
BSSID:"rweathers"
Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 18 Mb/s
24 Mb/s; 36 Mb/s; 54 Mb/s
Bit Rates:6 Mb/s; 9 Mb/s; 12 Mb/s; 48 Mb/s
Mode:Ad Hoc

In this example, the BSSID you need to fill in is rweathers.