About iw

iw is a new nl80211 based CLI configuration utility for wireless devices. Currently you can only use this utility to configure devices which use a mac80211 driver as these are the new drivers being written – only because most new wireless devices being sold are now SoftMAC. Please see our list of mac80211 drivers.

iw is still under development. Features are added 'as we go'. The only documentation that exists for iw is this page. Please help expand it

Getting iw

Release tarballs of iw are available from http://wireless.kernel.org/download/iw/.

Alternatively, you can download iw from git: http://git.sipsolutions.net/iw.git, the web interface can also create tarballs for arbitrary revisions.

Using iw requires you to have at least libnl-1.0 pre8 as this release introduced genl, Generic Netlink, which nl80211 relies on. Most distributions aren't shipping this yet, although Debian Sid and OpenSUSE 11 contains version 1.1. If your distribution's libnl is insufficiently recent, you'll have to download and compile libnl yourself for now.

Libnl homepage: http://people.suug.ch/~tgr/libnl/

Note also that iw requires a recent version of the header file 'nl80211.h'; if the version on your system is too old, try using the version from wireless-testing.

Adding interfaces with iw

The command line is:

iw phy phy0 interface add moni0 type monitor

where you can replace monitor by anything else and moni0 by the interface name, and need to replace phy0 by the PHY name for your hardware (usually phy0 will be correct unless you hotplugged or reloaded any modules.) If your udev is configured incorrectly, the newly created virtual interface may be renamed by it right away, use ip link to list all interfaces.

Modifying monitor interface flags

You can customize the type of monitor interface you create. This can be very useful for debugging purposes on end user systems. For example suppose you want to help a user you can take advantage of the fact that a monitor interface in mac80211 uses radiotap to pass up to userspace additional data. Say we want to help a user fish out data without affecting the device's performance by setting it it to a full monitor interface an monitor interface with no additional monitor flags can be created as follows:

sudo iw dev wlan0 interface add fish0 type monitor flags none

You can then request the user to use tcpdump on a session:

tcpdump -i fish0 -s 65000 -p -U -w  /tmp/fishing.dump

Monitor flags possible

The following are flags you can specify:

• none
• fcsfail
• plcpfail
• control",
• otherbss",
• cook

Deleting interfaces with iw

The command line is:

iw dev moni0 del

Where "moni0" was the virtual interface interface that was created with the first command

Updating your regulatory domain

The command line is:

iw reg set alpha2

Where "alpha2" is the ISO/IEC 3166 alpha2 country code. The information used and set comes from our regulatory infrastructure.