Wifi tethering using Ubuntu

If you are having trouble with wifi tethering on Ubuntu, your problem may well be caused by Ubuntu’s inconvenient treatment of ad-hoc wireless networking.

Just put your wifi card into ad-hoc mode manually and you are ready to go.

ifconfig wlan0 down
iwconfig wlan0 mode Ad-Hoc

You only have to do this once. Afterwards Ubuntu will readily allow ad-hoc wireless networking.