[Guy Harris <gharris@xxxxxxxxx>]

Alvin Lim wrote:

> As i know ethereal is biuld upon on winPcap.

Ethereal uses WinPcap, on Windows, to do traffic capture; it uses 
libpcap on UN*X.

> May i know, can ethereal or winpcap capture signal strength or noise of 
> a wireless client.

Ethereal can, but not on Windows...

...because WinPcap can't.  WinPcap has a driver that connects to network 
adapter drivers, but it doesn't include any network adapter drivers - it 
relies on the capabilities of network adapter drivers in the system, 
and, as far as I know, none of the vendor-supplied or Microsoft-supplied 
drivers supplied for 802.11 network adapters on Windows support 
supplying radio information such as signal strength with captured packets.

Ethereal *can* do so on Linux, and on some BSD systems, with some 
adapters and drivers.