A family relative has a ThinkPad on which I installed Kubuntu 9.04 after it went gold, three years ago. While they frequently visit us about every three months (she and my wife go shopping and he and I go to the shooting range and terrorize some targets) in all those three years she never once mentioned any problems with her Kubuntu installation. Last week she called up and said Kubuntu would no longer connect to the Internet. That eliminated any remote connection to look at the desktop, so she and my wife scheduled another day of shopping! 
I thought it would be an easy fix. When I discussed the circumstances she mentioned something about inadvertently hitting the "sleep" button instead of the power off button. The problem appeared when she next turned it on and tried to make a banking connection. "The browser wouldn't work."
I noticed this odd message “Networking interface unmanaged” in the Network icon on the system tray, which is supposed to display a list of wireless APs.
My first thought was that the NetworkManager.state variable:
/var/lib/NetworkManager/NetworkManager.state
[main]
NetworkingEnabled=true
...
contained "false" instead. It did! Triumphantly I reset it to "true" and ran "sudo service networking restart" The NetworkManager still refused to allow a network connection. I spent the next two hours googleing launchpad and every other website. After trying many false leads I decided to use the recovery mode and see what I could do there. I started the network from the recovery console and logged into a console as root. Ifconfig showed I had an eth0 connection and I could ping google.com. I used startx to start the KDE desktop, expecting to see a working network connection with a list of the 30 or so wireless APs in my area. No Joy!
But, I could use dpkg and check for broken packages, which turned up nothing. Since I had an eth0 connection despite the NetworkManager refusing to recognize it or allow a wireless connection I started the upgrade to Kubuntu 12.04. It took just under an hour. I figured that the upgrade would repair things and that by doing the upgrade I'd kill two birds with one stone. After the upgrade I rebooted. No Joy, but I still could get an eth0 connection from recovery. So, installed wicd and could create both an eth0 and a wifi connection as her user. (That should have told me something but my brain has grown increasingly more dense as time passes.)
Then my she and my wife returned from shopping and it was time to admit defeat.
I desperately tried one more google listing and learned something I didn't know. I was looking at the word "unmanaged" and thinking "the network is disabled". Not only is there a switch on networking, there is one on the NetworkManager itself as well. Once I thought about it it made perfect sense.
It turns out there is a config for the NetworkManager itself, besides the config for the networks connections.
sudo kwrite /etc/NetworkManager/NetworkManager.conf
revealed that the conf file had the following:
[ifupdown]
managed=false
I change the "false" to "true" and the list of wireless AP's appeared. Everything now worked as it should. I rebooted and checked just to be sure. It stuck. We all went out for Chinese dinners.
Now, if only I could get my brain to working like it used to ...
P.S. -- That's the only problem she's had with her Kubuntu installation in three years! Now, we'll see how well the 12.04 release works for her. It's been working great for me!
I thought it would be an easy fix. When I discussed the circumstances she mentioned something about inadvertently hitting the "sleep" button instead of the power off button. The problem appeared when she next turned it on and tried to make a banking connection. "The browser wouldn't work."
I noticed this odd message “Networking interface unmanaged” in the Network icon on the system tray, which is supposed to display a list of wireless APs.
My first thought was that the NetworkManager.state variable:
/var/lib/NetworkManager/NetworkManager.state
[main]
NetworkingEnabled=true
...
contained "false" instead. It did! Triumphantly I reset it to "true" and ran "sudo service networking restart" The NetworkManager still refused to allow a network connection. I spent the next two hours googleing launchpad and every other website. After trying many false leads I decided to use the recovery mode and see what I could do there. I started the network from the recovery console and logged into a console as root. Ifconfig showed I had an eth0 connection and I could ping google.com. I used startx to start the KDE desktop, expecting to see a working network connection with a list of the 30 or so wireless APs in my area. No Joy!
But, I could use dpkg and check for broken packages, which turned up nothing. Since I had an eth0 connection despite the NetworkManager refusing to recognize it or allow a wireless connection I started the upgrade to Kubuntu 12.04. It took just under an hour. I figured that the upgrade would repair things and that by doing the upgrade I'd kill two birds with one stone. After the upgrade I rebooted. No Joy, but I still could get an eth0 connection from recovery. So, installed wicd and could create both an eth0 and a wifi connection as her user. (That should have told me something but my brain has grown increasingly more dense as time passes.)
Then my she and my wife returned from shopping and it was time to admit defeat.
I desperately tried one more google listing and learned something I didn't know. I was looking at the word "unmanaged" and thinking "the network is disabled". Not only is there a switch on networking, there is one on the NetworkManager itself as well. Once I thought about it it made perfect sense.
It turns out there is a config for the NetworkManager itself, besides the config for the networks connections.
sudo kwrite /etc/NetworkManager/NetworkManager.conf
revealed that the conf file had the following:
[ifupdown]
managed=false
I change the "false" to "true" and the list of wireless AP's appeared. Everything now worked as it should. I rebooted and checked just to be sure. It stuck. We all went out for Chinese dinners.
Now, if only I could get my brain to working like it used to ...
P.S. -- That's the only problem she's had with her Kubuntu installation in three years! Now, we'll see how well the 12.04 release works for her. It's been working great for me!