NAME

     wlan — generic 802.11 link-layer support

SYNOPSIS

     device wlan

DESCRIPTION

     The wlan module provides generic code to support 802.11 drivers.  Where a device does not
     directly support 802.11 functionality this layer fills in.  The wlan module is required by
     all native 802.11 drivers as well as the ndis(4) support.

     wlan supports multi-mode devices capable of operating in both 2.4GHz and 5GHz bands and
     supports numerous 802.11 standards: 802.11a, 802.11b, 802.11g, 802.11n, and 802.11s (Draft
     3.0).  The WPA, 802.11i, and 802.1x security protocols are supported through a combination
     of in-kernel code and user-mode applications.  The WME/WMM multi-media protocols are
     supported entirely within the wlan module but require a suitably capable hardware device.
     Likewise the 802.11h specification is supported only by suitably capable devices.

     Drivers provide 802.11 functionality through wlan interfaces that are created at runtime
     using interface cloning.  This is done with the ifconfig(8) create command or using the
     wlans_IFX variable in rc.conf(5).  Some drivers support the creation of multiple wlan
     interfaces that share the same underlying device; this is the way by which ``multi-bss
     support'' is provided but it can also be used to create WDS links and other interesting
     applications.

     There are several types of wlan interfaces that may be created:

     sta      A client station in an infrastructure bss (i.e. one that associates to an access
              point).

     hostap   An access point in an infrastructure bss.

     mesh     A mesh station in an MBSS network.

     adhoc    A station in an IBSS network.

     ahdemo   A station operating in ``adhoc demo mode''.  This is essentially an IBSS station
              that does not use management frames (e.g. no beacons are transmitted).  An ahdemo
              interface is especially useful for applications that want to transmit and receive
              raw 802.11 packets.

     monitor  An interface used exclusively for capturing 802.11 frames.  In particular this
              specified to have read-only properties which enables it to be operated on
              frequencies where one would otherwise not be allowed.

     wds      A station that passes 4-address 802.11 traffic for the purpose of tunneling traffic
              over a wireless link.  Typically this station would share the same MAC address as a
              hostap interface.  It may be possible to create wds interfaces without a companion
              hostap interface but that is not guaranteed; one may need to create a hostap
              interface that does not send beacon frames before wds interfaces may be created.

     Note that an interface's type cannot be changed once it is created.

     wlan defines several mechanisms by which plugin modules may be used to extend its
     functionality.  Cryptographic support such as WEP, TKIP, and AES-CCMP are implemented as
     standalone modules (if not statically configured into a system) that register with wlan.
     Similarly there is an authenticator framework for defining 802.11 authentication services
     and a framework for integrating access control mechanisms specific to the 802.11 protocol.

DEBUGGING

     If the IEEE80211_DEBUG option is included in the kernel configuration, debugging controls
     are available using:

           sysctl net.wlan.X.debug=mask

     where X is the number of the wlan instance and mask is a bit-or of control bits that
     determine which debugging messages to enable.  For example,

           sysctl net.wlan.0.debug=0x00200000

     enables debugging messages related to scanning for an access point, adhoc neighbor, or an
     unoccupied channel when operation as an access point.  The wlandebug(8) tool provides a more
     user-friendly mechanism for doing the same thing.  Note that

           sysctl net.wlan.debug=mask

     defines the initial value of the debugging flags for each cloned wlan interface; this is
     useful to enable debug messages during interface creation.

COMPATIBILITY

     The module name of wlan was used to be compatible with NetBSD.

     Mesh stations follow the 802.11s Draft 3.0 specification which is not ratified and subject
     to change.  Beware that this specification is incompatible with earlier drafts; and stations
     implementing earlier drafts (e.g. Linux) may not interoperate.

SEE ALSO

     an(4), ath(4), bwi(4), bwn(4), ipw(4), iwi(4), iwm(4), iwn(4), malo(4), mwl(4), netintro(4),
     otus(4), ral(4), rsu(4), rtwn(4), rum(4), run(4), uath(4), upgt(4), ural(4), urtw(4), wi(4),
     wlan_acl(4), wlan_ccmp(4), wlan_tkip(4), wlan_wep(4), wlan_xauth(4), wpi(4), zyd(4)

STANDARDS

     More information can be found in the IEEE 802.11 Standards.

HISTORY

     The wlan driver first appeared in FreeBSD 5.0.

AUTHORS

     Atsushi Onoe is the author of original NetBSD software from which this work began.  Sam
     Leffler brought the code into FreeBSD and then rewrote it to support multi-mode devices,
     802.11g, 802.11n, WPA/802.11i, WME, multi-bss, and add the extensible frameworks for
     cryptographic, authentication, and access control plugins.  This manual page was written by
     Tom Rhodes <trhodes@FreeBSD.org>.