Does it work with iwconfig?
sudo iwconfig wlan0 essid network_essid key s:password
If your Kubuntu uses name eth1 for the wireless ethernet card rather than wlan0, change it to the commands above (eth0 is usually your wired ethernet device). Also note that you'll use the form s:password if your password is ASCII, but if it's instead in hex, just drop off the s: (in ascii: key s:password
, in hex: key password
). And if there are special letters, try quoting the essid/password to escape them.
If it connects that way, the problem is in the application you usually use to connect to networks; either it assumes the key wrong (ascii/hex) or does something else the wrong way..but if iwconfig method fails too, it's something more interesting.
I'm not sure, but you might have to bring the interface up before doing that (if it says no such interface); in that case use
and if you want it down, respectively
ifconfig wlan0 down
Note that on command line you'll use if
config to bring devices up/down and configure wired devices, but when configuring wireless devices (no encryption or WEP), you'll use iw
config instead. For WPA encryption (on command line) you'll need to use something like wpa_supplicant instead; iwconfig doesn't do WPA as far as I know.