Iw: what’s the default channel bandwidth

networkingwifi

I'm using the iw tool to configure a WiFi interface to sniff the air (monitor mode) on specific channel:

ifconfig wlan0 down
iw dev wlan0 set channel 1
iwconfig wlan0 mode monitor
ifconfig wlan0 up

The manpage for iw says that the channel bandwidth is optional:

dev <devname> set channel <channel> [HT20|HT40+|HT40-]

But it's not clear what value of the three is the default and according to what it's chosen?

Using Ubuntu Ubuntu 12.04.4, kernel 3.5.0-45-generic.

Best Answer

There is no default, because it always depends the hardware capabilities and the configuration. They are always negotiated at handshake stage. To see your WiFi capabilites use

iw phy

See also HT20/40.

Some tcpdump wireless filters.

Related Question