monitor versus hostscan ioctl?

Jouni Malinen jkmaline
Thu Nov 6 18:51:58 PST 2003

On Thu, Nov 06, 2003 at 11:52:08AM -0800, Ichiro Barnes wrote:

> - You use monitor to put received frames, including
> 802 headers, into user space so libpcap'ed
> applications like Ethereal can see them. These frames
> cover everything, from beacons to data frames. You can
> use this ioctl with fairly old (v. 12?) versions of
> Wireless Extensions, and you can maintain your current
> association in this mode.

Monitor mode makes all received frames available for user space
programs. These frames can then be received, e.g., with a raw packet
socket (libpcap is just one way of implementing this).

ioctl itself just configures the driver into this mode. Otherwise,
wireless extensions are not involved.

Monitor mode does _not_ allow you to maintain any association.

> - You use hostscan when you're just looking for
> beaconing information. The results are reported to the
> command line, so no additional applications are
> needed. You will need version 14 or greater of the
> Wireless Extensions to do this. You will however need
> fw greater than rev. 1.3.1 on your wireless card. You
> can maintain your current association in this mode.

I'm not fully sure what you mean with hostscan. You can use iwpriv and
the private hostscan parameter and then see the results in kernel log.
The more standard way of doing this is to use iwlist and 'scan' command
(which, in case of Host AP driver, uses either hostscan or "old scan"
based on the firmware version, so this has at least limited
functionality even with older firmware versions).

Jouni Malinen                                            PGP id EFC895FA

More information about the Hostap mailing list