can't change channel of my wifi interface using aircrack

Question

Whenever I try to listen to a specific wifi channel using airodump I got : fixed channel wlan0: -1
I try to change the channel but it's always -1!

I use Ubuntu 12.04.

Answer 1

What you have to do is execute ifconfig wlan0 down

make sure you are not connected to any wireless network, try:
airodump-ng -<the channel you want> --bssid<the wireless network you want> mon0

If it doesn't work, try:

• ifconfig wlan0 down then
• ifconfig mon0 down then
• iwconfig mon0 mode monitor then
• ifconfig wlan0 up then
• ifconfig mon0 up and try to sniff now.