I broke my wlan0 interface

[muton]

My network was connected and i ran 'ifconfig wlan0 down' not thinking how bad this could be and now when I open the Network Manager widget the wireless AP's do not show up and it stays stuck on "not updated yet" and "IP Address: dum.my.ip.a". I still get results with 'iwlist wlan0 scan'.

I'm using 9.04 Jaunty Jackalope Kubuntu.

[D-cat]

ifup wlan0

[muton]

I tried ifconfig wlan0 up, is there a big difference?
I will try ifup.

[muton]

sudo ifup wlan0 does not connect, eventually the dhcp client goes to sleep saying no leases offered.

[D-cat]

A: they're synonyms

B: That's normal when there's no unencrypted access points available. Set up for your AP after and it should work. You can use the wireless network manager or from the cli:
sudo iwconfig wlan0 essid your_AP key yourWEPkey [1]

In some cases, after connecting to the AP, it still fails to set up the network settings. If that happens, I think Ubuntu uses dhclient to give dhcp a kick (just type sudo dhclient at the prompt if you can't use the connection after about 10 seconds or so).

[muton]

I'm using wpa encryption, so I configured wpa_supplicant then tried using "wpa_supplicant -Dwext -iwlan0 -c/etc/wpa_supplicant.conf", then "ifup wlan0" to connect. I did both of these as root. I don't know if this is the proper way to use wpa_supplicant or not.

[D-cat]

No, the ifup only brings the interface back up WITH DEFAULTS after it has been brought down. Doing that after you set up you connection could kill the connection.

First is the ifup

Then you set up the connection for your AP, whether with iwconfig or with wpa_supplicant

Finally, IF after making the "physical" connection you still can't use it, run dhclient.

---
edit: Also, looking at the wpa_supplicant man page, there should be a space between each option and its argument. (e.g. "-i wlan0" , not "-iwlan0")

I don't know enough about the wpa_supplicant to offer further help on it though.

[muton]

It's not working. As far as I can tell wpa_supplicant isn't associating with my AP.

[D-cat]

But it did work before?

[muton]

yes. Everything was working fine. What happened was I wanted to change my wireless card's mac address so i installed macchanger. Then i brought down wlan0 so I could make changes but I didn't think to stop networking first. I didn't even disconnect from NetworkManager