If you are having problems connecting to a wireless network with KnetworkManager try this:
1.) Boot from a LiveCD of the Version of Kubuntu that you use (this works for Ubuntu, too). Note: You should boot from the LiveCD to eliminate any problems you may have caused by altering settings inadvertently in the network manager in a hard drive installation. This is easy to do.
2.) Click on the Knetworkmanager icon in the taskbar (bottom right of screen in Kubuntu, top right in Ubuntu).
3.) A panel should open up showing choices for program preferences, and a list of available wireless networks. These networks are displayed by name (essid) in a line with a bar graph showing signal strength. Click on the network's line that you would like to connect to. If the network requires a password, a password dialog will open up and you should fill in the password to connect. (Note: be sure to select the right type for your router's encryption method WPA, WEP-128 bit, WEP-64 bit, passphrase or hex, etc)
If you do not see any network lines when you first open network manager, there are two possibilities:
a.) There are no networks of sufficient signal strength in your area (if at home, your wifi router may be turned off). Solution: move to an area where there are networks, or turn on your router.
b.) Your network wireless card is not working with your Kubuntu system. In this case you will have to delve into the requirements for your wireless card -- drivers, etc. this is covered elsewhere in wikis and documentation online.
Note: if you do see network lines and bar graphs when opening KNetworkManager from LiveCD, it is almost certain that you do have proper card drivers installed, and you should not try to troubleshoot card drivers!
4.) If you are able to successfully connect to a network by clicking on the particular network line you want in LiveCD mode, but you are unable to see those same networks from an installed hard drive version of Kubuntu, the most likely cause of the problem is an altered file called /etc/network/interfaces
To solve this (thanks to user elabranche!), check the contents of the file against the following. This file works for a large number of users who have reported problems:
auto lo
iface lo inet loopback
address 127.0.0.1
netmask 255.0.0.0
auto eth0
iface eth0 inet dhcp
auto eth1
iface eth1 inet dhcp
auto eth2
iface eth2 inet dhcp
auto wlan0
iface wlan0 inet dhcp
auto ath0
#iface ath0 inet dhcp
If the file doesn't look like this, "save as" a version of your old file with a .bak extension, so you can restore it if you need to, edit the original file and change it to the above, or copy and paste the above in place of what is there. (New note: See second post below about ath0 -- your network card's device name may vary)
Then reboot. The KnetworkManager should now behave as the CD version did.
5.) If for some reason this does not solve your KNetworkManager problems, you may need to uninstall and re-install KNetworkManager (I did because mine had gotten corrupted in a power outtage during a save).
Note that if you uninstall it, you may not be able to connect to the internet to re-install it, depending on what other network software you have available -- or your skills in connecting via the console. Or whether a wired connection is also available to you.
I solved the disconnect problem at home by temporaraily setting my router to unencrypted and no WPA, and typing the following into the console of my Kubuntu machine:
sudo ath0 essid your network's name here
sudo ath0 channel your network's channel number here
sudo dhclient ath(0)
(Note: Substitute wlan0 for ath0, above, if your wireless card doesn't use Atheros chips -- as mine does).
I don't know if the channel is necessary -- but it resolved faster for me. Likewise use dhclient only if your router is set up for DHCP assignment.
If you want info on your network's name (router name or essid) use the following command
sudo iwlist ath0 scanning
6.) After you are connected you can reinstall Knetworkmanager using Adept or any other package manager you normally use. Don't forget to re-set your router to the encryption method and passwords you normally use after you have downloaded and re-installed your network manager.
Notes:
Many of the problems occur because people do not realize that the way to connect is by clicking a bar-graph network line when first opening the Networkmanager icon. Clicking the signal graph display is a non-intuitive way of adding a password.. They try other options in the drop down preferences list to try to connect and/or add WPA passwords etc. -- sometimes by turning off roaming, and adding entries manually. Then they try to save this new configuration for loading when Ubuntu starts up. The effect of this change is to alter the etc/network/interfaces file so that auto-scanning of networks is now disabled. The program now tries to open only the connection they specified manually -- no other networks are visible, and often the one they specified was incorrectly set up or they have moved their location and it is no longer available. Restoring the interfaces file as above removes the saved manual entry, and auto scanning is restored.
People also often assume that because they see their preferred network in the drop down list, but aren't yet connected, that they have problems with their wifi network card drivers. So they attempt to add ndiswrapper drivers, etc.This can make things worse.
Most of these user problems are NOT due to driver problems, but a simple misunderstanding of how to use the program to connect to a wireless netwok.
1.) Boot from a LiveCD of the Version of Kubuntu that you use (this works for Ubuntu, too). Note: You should boot from the LiveCD to eliminate any problems you may have caused by altering settings inadvertently in the network manager in a hard drive installation. This is easy to do.
2.) Click on the Knetworkmanager icon in the taskbar (bottom right of screen in Kubuntu, top right in Ubuntu).
3.) A panel should open up showing choices for program preferences, and a list of available wireless networks. These networks are displayed by name (essid) in a line with a bar graph showing signal strength. Click on the network's line that you would like to connect to. If the network requires a password, a password dialog will open up and you should fill in the password to connect. (Note: be sure to select the right type for your router's encryption method WPA, WEP-128 bit, WEP-64 bit, passphrase or hex, etc)
If you do not see any network lines when you first open network manager, there are two possibilities:
a.) There are no networks of sufficient signal strength in your area (if at home, your wifi router may be turned off). Solution: move to an area where there are networks, or turn on your router.
b.) Your network wireless card is not working with your Kubuntu system. In this case you will have to delve into the requirements for your wireless card -- drivers, etc. this is covered elsewhere in wikis and documentation online.
Note: if you do see network lines and bar graphs when opening KNetworkManager from LiveCD, it is almost certain that you do have proper card drivers installed, and you should not try to troubleshoot card drivers!
4.) If you are able to successfully connect to a network by clicking on the particular network line you want in LiveCD mode, but you are unable to see those same networks from an installed hard drive version of Kubuntu, the most likely cause of the problem is an altered file called /etc/network/interfaces
To solve this (thanks to user elabranche!), check the contents of the file against the following. This file works for a large number of users who have reported problems:
auto lo
iface lo inet loopback
address 127.0.0.1
netmask 255.0.0.0
auto eth0
iface eth0 inet dhcp
auto eth1
iface eth1 inet dhcp
auto eth2
iface eth2 inet dhcp
auto wlan0
iface wlan0 inet dhcp
auto ath0
#iface ath0 inet dhcp
If the file doesn't look like this, "save as" a version of your old file with a .bak extension, so you can restore it if you need to, edit the original file and change it to the above, or copy and paste the above in place of what is there. (New note: See second post below about ath0 -- your network card's device name may vary)
Then reboot. The KnetworkManager should now behave as the CD version did.
5.) If for some reason this does not solve your KNetworkManager problems, you may need to uninstall and re-install KNetworkManager (I did because mine had gotten corrupted in a power outtage during a save).
Note that if you uninstall it, you may not be able to connect to the internet to re-install it, depending on what other network software you have available -- or your skills in connecting via the console. Or whether a wired connection is also available to you.
I solved the disconnect problem at home by temporaraily setting my router to unencrypted and no WPA, and typing the following into the console of my Kubuntu machine:
sudo ath0 essid your network's name here
sudo ath0 channel your network's channel number here
sudo dhclient ath(0)
(Note: Substitute wlan0 for ath0, above, if your wireless card doesn't use Atheros chips -- as mine does).
I don't know if the channel is necessary -- but it resolved faster for me. Likewise use dhclient only if your router is set up for DHCP assignment.
If you want info on your network's name (router name or essid) use the following command
sudo iwlist ath0 scanning
6.) After you are connected you can reinstall Knetworkmanager using Adept or any other package manager you normally use. Don't forget to re-set your router to the encryption method and passwords you normally use after you have downloaded and re-installed your network manager.
Notes:
Many of the problems occur because people do not realize that the way to connect is by clicking a bar-graph network line when first opening the Networkmanager icon. Clicking the signal graph display is a non-intuitive way of adding a password.. They try other options in the drop down preferences list to try to connect and/or add WPA passwords etc. -- sometimes by turning off roaming, and adding entries manually. Then they try to save this new configuration for loading when Ubuntu starts up. The effect of this change is to alter the etc/network/interfaces file so that auto-scanning of networks is now disabled. The program now tries to open only the connection they specified manually -- no other networks are visible, and often the one they specified was incorrectly set up or they have moved their location and it is no longer available. Restoring the interfaces file as above removes the saved manual entry, and auto scanning is restored.
People also often assume that because they see their preferred network in the drop down list, but aren't yet connected, that they have problems with their wifi network card drivers. So they attempt to add ndiswrapper drivers, etc.This can make things worse.
Most of these user problems are NOT due to driver problems, but a simple misunderstanding of how to use the program to connect to a wireless netwok.
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