This offloads the station polling to driver wrappers, which may offload
it again to the driver. The hostap driver wrapper uses "real" data
frames while nl80211 uses null data frames.
Also add a specific event to indicate that a poll was successful for
future use with the nl80211 driver.
Remove the separate driver_ops functions set_cts_protect(),
set_preamble(), set_short_slot_time(), and set_ht_params(). These
belong into same set of operations as set_ap(), so there is no need
to maintain separate functions that just make the driver wrapper
more complex.
Since these have only been used with driver_nl80211.c, the driver_ops
can be removed immediately instead of maintaining backwards
compatibility period with the old functions.
The AP client isolation parameter is now available through set_ap().
driver_nl80211.c was the only driver wrapper using the set_intra_bss()
call in hostap.git, but some external trees may have used this. Once
those are cleared, the set_infra_bss() driver_ops can be removed
completely. The only remaining use case for it currently is in P2P
GO mode with wpa_supplicant.
Pass SSIDs to be matched in scheduled scan results. Only the SSIDs
that are included in the match lists will be reported by the driver,
so the filtering can be offloaded to the hardware and the power
consumption can be reduced.
Signed-off-by: Luciano Coelho <coelho@ti.com>
With scheduled scan support, we may need to pass more than 10 SSIDs in
a single scan request. Some drivers (e.g., wl12xx) support up to 16
SSIDs at once.
Change WPAS_MAX_SCAN_SSIDS from 10 to 16.
Signed-off-by: Luciano Coelho <coelho@ti.com>
In new Linux kernel versions (>=3.0), nl80211 adds scheduled scan
capability. In order to use this feature to its full extent, we need
to support it in the wpa_supplicant core, so that it can also be used
by other drivers.
This commit adds initial scheduled scan support operations and events.
Signed-off-by: Luciano Coelho <coelho@ti.com>
This new flag can be used to change wpa_supplicant behavior in the
default ap_scan=1 mode to move BSS selection into the driver (likely
firmware). This commit is only adding the flag; separate commits
will be used to change the actual connection/roaming behavior.
This allows drivers to disable CCK rates from Probe Request frames.
For nl80211, this is currently applying only to the supported rates
element(s), but this mechanism could be extended to address TX rate
control masking, too, to lessen need for global rate disabling.
Signed-off-by: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
The previous code was trying to figure out which WPA version is
used based on the extra IEs requested for Association Request. That
did not work properly in cases where non-WPA networks are used with
some extra IEs. Fix this by using more robust mechanism for passing
the WPA versions from core wpa_supplicant to the driver_ops
associate().
This allows the driver to use PS buffering of Deauthentication and
Disassociation frames when the STA is in power save sleep. The STA
entry (and PTK) will be removed from the kernel only after the
Deauth/Disassoc has been transmitted (e.g., when the STA wakes up).
A hardcoded two second timeout is used to limit the length of this
window should the driver fail to deliver the frame (e.g., the STA
is out of range and does not wake up). The kernel STA entry is
marked unauthorized during the wait to avoid accepting Data
frames from the STA that we have decided to disconnect.
This behavior is available only with drivers that provide TX status
events for Deauth/Disassoc frames (nl80211 at this point). Other
drivers continue to use the previous behavior where the STA entry
is removed immediately.
This change is a first step in better supporting different driver
architectures for AP mode operations with nl80211. This commit in
itself does not add new functionality, but it makes it easier to add
new AP mode parameters to address needs of drivers that have more of
the MLME/SME in firmware or kernel.
Currently, wpa_driver_nl80211_authenticate() changes the interface type
to station. However, in case of P2P, we need to change the interface
type to P2P_CLI.
Add p2p field to the authentication params, and consider it for choosing
the correct interface type.
Signed-off-by: Eliad Peller <eliad@wizery.com>
Only accept Probe Request frames that have a Wildcard BSSID and a
destination address that matches with our P2P Device Address or is the
broadcast address per P2P specification 3.1.2.1.1.
Add support to wpa_supplicant for device-based GTK rekeying. In order to
support that, pass the KEK, KCK, and replay counter to the driver, and
handle rekey events that update the latter.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
When adding a new station, set the STA flags as part of the sta_add()
command. This ensures the flags are up to date when the station is added
by lower level drivers.
Signed-off-by: Arik Nemtsov <arik@wizery.com>
This should fix EAPOL reauthentication and rekeying timeout issues
with Intel clients when using WMM (e.g., with IEEE 802.11n). These
stations do not seem to be able to handle EAPOL data frames as
non-QoS Data frames after the initial setup.
This adds STA flags to hapd_send_eapol() driver op to allow
driver_nl80211.c to mark the EAPOL frames as QoS Data frame
when injecting it through the monitor interface.
This provides a means for the supplicant to directly request signal
quality metrics from the driver. This is useful, for example for
background scan algorithms that might ask desire this information
out-of-band with CQM events.
Signed-off-by: Paul Stewart <pstew@google.com>
This allows driver wrappers to indicate whether the association was
done using Association Request/Response or with Reassociation
Request/Response frames.
Previously, both NULL and ff:ff:ff:ff:ff:ff addr were used in various
places to indicate default/broadcast keys. Make this more consistent
and useful by defining NULL to mean default key (i.e., used both for
unicast and broadcast) and ff:ff:ff:ff:ff:ff to indicate broadcast
key (i.e., used only with broadcast).
Use NULL instead of (u8 *) "" as the seq value and make sure the
driver wrapper implementations can handle NULL value. This was
previously already done in number of places, but not everywhere.
This adds partial callbacks and events to allow P2P management to be
implemented in a driver/firmware. This is not yet complete and is
very much subject to change in the future.
With the new kernel functionality coming to Linux to allow off-channel
TX, we can take advantage of that in the P2P code that currently uses
remain-on-channel. If a driver advertises support for it, it will be
asked to handle off-channel TX by itself.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
The nl80211 driver can report low ACK condition (in fact it reports
complete loss right now only). Use that, along with a config option, to
disconnect stations when the data connection is not working properly,
e.g., due to the STA having went outside the range of the AP. This is
disabled by default and can be enabled with disassoc_low_ack=1 in
hostapd or wpa_supplicant configuration file.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
If a station received unprotected Deauthentication or Disassociation
frame with reason code 6 or 7 from the current AP, there may be a
mismatch in association state between the AP and STA. Verify whether
this is the case by using SA Query procedure. If not response is
received from the AP, deauthenticate.
This implementation is only for user space SME with
driver_nl80211.c.
When controlling multiple virtual interfaces on the same physical
radio, share the scan results events with sibling interfaces. This
decreases the time it takes to connect many virtual interfaces.
This is currently only supported on Linux with cfg80211-based
drivers when using nl80211 or wext driver interface.
Signed-off-by: Ben Greear <greearb@candelatech.com>
Some drivers are not providing exactly reliable error codes (e.g.,
with WEXT), but others may actually indicate reliable information.
Allow driver wrappers to indicate if that is the case and use
optimizations if so. For now, this improves nl80211 with
NL80211_CMD_CONNECT for a case where connection request fails.
WPA_DRIVER_FLAGS_P2P_MGMT_AND_NON_P2P flag can now be used to
indicate that the initial interface (e.g., wlan0) is used for
P2P management operations and potentially non-P2P connections.
This is otherwise identical to
WPA_DRIVER_FLAGS_P2P_DEDICATED_INTERFACE, but the possibility of
non-P2P connections makes some operations differ.
The driver wrapper may now indicate the preferred channel (e.g., based
on scan results) on both 2.4 GHz and 5 GHz bands (and an overall best
frequency). When setting up a GO, this preference information is used
to select the operating channel if configuration does not include
hardcoded channel. Similarly, this information can be used during
GO Negotiation to indicate preference for a specific channel based
on current channel conditions.
p2p_group_add command can now use special values (freq=2 and freq=5)
to indicate that the GO is to be started on the specified band.
These are not used by any driver wrapper, i.e., only the four
data queues (BK, BE, VI, VO) are configurable. Better remove these
so that there is no confusion about being able to configure
something additional.
Add a new driver event, EVENT_INTERFACE_UNAVAILABLE, for indicating
that the driver is not able to continue operating the virtual
interface in its current mode anymore, e.g., due to operating
channel for GO interface forced to a DFS channel by another virtual
interface.
When this happens for a P2P group interface, the P2P group will
be terminated and P2P-GROUP-REMOVED event shows the reason for
this as follows:
P2P-GROUP-REMOVED wlan0 GO reason=UNAVAILABLE
The driver wrapper can now indicate whether the driver supports
concurrent operations on multiple channels (e.g., infra STA connection
on 5 GHz channel 36 and P2P group on 2.4 GHz channel 1). If not,
P2P_CONNECT commands will be rejected if they would require
multi-channel concurrency.
The new failure codes for P2P_CONNECT:
FAIL-CHANNEL-UNAVAILABLE:
The requested/needed channel is not currently available (i.e., user has
an option of disconnecting another interface to make the channel
available).
FAIL-CHANNEL-UNSUPPORTED:
The request channel is not available for P2P.
WPS 2.0 mandates the AP to include WPS IE in (Re)Association Response
if the matching (Re)Association Request included WPS IE. Provide the
needed WPS IE information to the driver_ops API for drivers that
process association frames internally.
Note: This modifies the driver_ops API by adding a new argument to
set_ap_wps_ie().
This is needed to be able to change parameters for dynamically
created interfaces between the creation of the interface and
association/start AP commands.
Following ctrl_interface commands can now be used:
P2P_SET client_apsd disable
- disable configuration (i.e., use driver default) in client mode
P2P_SET client_apsd <BE>,<BK>,<VI>,<VO>;<max SP Length>
- enable UASPD with specific trigger configuration (0/1) per AC
(max SP Length is currently ignored)
P2P_SET go_apsd disable
- disable configuration (i.e., use driver default) in AP mode
P2P_SET go_apsd <0/1>
- disable/enable APSD in AP mode
Some NDIS drivers require a workaround to allow them to associate
with a WPS AP that is already using protection (Privacy field = 1).
Let driver_ndis.c know if the AP is already using Privacy and if so,
configure a dummy WEP key to force the driver to associate.
Add a new wpa_supplicant state: interface disabled. This can be used
to allow wpa_supplicant to be running with the network interface even
when the driver does not actually allow any radio operations (e.g.,
due to rfkill).
Allow driver_nl80211.c and driver_wext.c to start while rfkill is in
blocked state (i.e., when ifconfig up fails) and process rfkill
events to block/unblock WLAN.
This adds more details into the CTRL-EVENT-DISCONNECTED event to
make it easier to figure out which network was disconnected in some
race conditions and to what could have been the reason for
disconnection. The reason code is currently only available with
the nl80211 driver wrapper.
There is no absolute requirement for separating address allocation
into separate functions, so simplify the driver wrapper interface
to use just if_add and if_remove instead of adding the new
alloc_interface_addr() and release_interface_addr() functions.
if_add() can now indicate if the driver forced a different interface
name or address on the virtual interface.
This can be used to test 802.11w by sending a protected or unprotected
deauth/disassoc frame.
hostapd_cli deauth <dst addr> test=<0/1>
hostapd_cli disassoc <dst addr> test=<0/1>
test=0: unprotected
test=1: protected
This patch allows the nl80211 driver to create its own per-bss context
and pass it to the drv_priv pointer of the hostapd bss state.
With this and the following patch, stations can associate to and switch
between multiple BSS interfaces of a single wiphy.
This obsoletes a few instances of passing ifname to a callback, those
can be removed in a separate patch.
It might also be useful to move more fields from the driver data to the
per-bss data structure in the future.
filter_ssids=1 global configuration parameter can now be used to
enable scan result filtering (with -Dnl80211 only for now) based on
the configured SSIDs. In other words, only the scan results that have
an SSID matching with one of the configured networks are included in the
BSS table. This can be used to reduce memory needs in environments that
have huge number of APs.
wpa_supplicant can now be notified of suspend/resume events, e.g.,
from pm-action scripts. This allows wpa_supplicant to clear information
that may become invalid during a suspend operation.
Some drivers may need to use a specific ifname for the virtual
interface, so allow them to do this with a new parameter passed
to the alloc_interface_addr() handler.
This allows the driver wrappers to return two sets of IEs, so that
the BSS code can use information from both Beacon and Probe Response
frames if needed. For example, some Cisco APs seem to include more
information in Wireless Provisioning Services IE when it is in the
Beacon frame.
The three existing enums were already depending on using the same
values in couple of places and it is just simpler to standardize on
one of these to avoid need for mapping between different enums for
the exact same thing.
Most of this file was already moved into wpa_supplicant/scan.c and
we can remove the file completely by having couple of small helper
functions copied to the remaining users outside core wpa_supplicant
code.
This fits better in wpa_supplicant/scan.c. Couple of remaining
scan_helpers.c functions are currently used in driver wrappers,
but they can likely be removed in the future.
This adds new commands and events for allowing off-channel Action
frame exchanges to be requested. This functionality is not yet used
and is only fully supported by driver_test.c at this point.
driver_nl80211.c has support for the remain-on-channel commands, but
the Action frame TX/RX part is still pending review for the kernel
code and as such, is not yet included here.
This adds placeholder code for allowing the virtual interfaces to be
pre-allocated a MAC address before the interface type is known with
drivers that do not handle interface type changes.
Get rid of wpa_supplicant_sta_rx() and add a new driver event that is
marked to be used only with driver_test.c. In addition, remove this
functionality from privsep wrapper. This is only use for client mode
MLME testing with driver_test.c.
Get more information about scans when updating BSS table information.
This allows the missing-from-scans expiration rule to work properly
when only partial set of channels or SSIDs are being scanned.
set_ap_wps_ie() is not used to set WPS IE for both Beacon and Probe
Response frames with a single call. In addition, struct wpabuf is used
instead of separate u8* and length fields. This avoids duplicated
allocation of the IEs and simplifies code in general.
This mode allows associated stations to use 4-address frames to allow
layer 2 bridging to be used. At least for the time being, this is only
supported with driver=nl80211.
Replace driver wrapper calls to hostapd_tx_status(),
hostapd_rx_from_unknown_sta(), hostapd_mgmt_rx(), and
hostapd_mgmt_tx_cb() with new generic driver events
EVENT_TX_STATUS, EVENT_RX_FROM_UNKNOWN, and EVENT_RX_MGMT.
This cleans up lot of the driver wrapper code to be less dependent
on whether it is being used within wpa_supplicant AP mode or hostapd.
This remove the need from driver_test.c to go through internal hostapd
structures to find the appropriate BSS when reporting events on secondary
BSSes.
This removes need for including hostapd/sta_flags.h into driver
wrappers and removes any remaining dependencies between driver flags
and internal hostapd flags.
IEEE 802.11w uses distinct key indexes (4 and 5) so the same
get_seqnum() handler can be used to fetch packet number for both
TKIP/CCMP and BIP(using IGTK).
Since the new get_seqnum_igtk() handler was not actually implemented by
any driver wrapper, this may also fix BIP/IGTK sequence number reporting
with driver_nl80211.c.
There was code for configuring this, but no driver wrapper actually
implements the actual setting. Remove this for now to reduce potential
confusion and to simply the driver interface.
In addition to the bitrate, the only other variable in this structure
is used internally in hostapd. Move this structure into hostapd.h and
make the driver API use simpler data structure (array of bitrates).
These are not really used and can be removed to clean up the driver
interface definition. The only remaining flag (HOSTAPD_RATE_BASIC) can
be removed once the basic rate set indication can be handled
differently.
if_add/if_remove can now be used as the generic driver ops for adding
and removing virtual interfaces of various types. In addition,
driver_nl80211.c is now including this code unconditionally, so that
the functions are not limited only for hostapd.
Print what the kernel believes the current BSS status (authenticated
or associated) is in scan results. In addition, check whether this
matches with the state that wpa_supplicant believes the driver to be
in.
This does not change the actual behavior, but will provide information
that will help in debugging potential issues where cfg80211/mac80211
seems to get into a different state from wpa_supplicant. In addition,
this provides an easy location for a workaround that could be added to
clear cfg80211/mac80211 state for unknown BSSes.
This makes it clearer which files are including header from src/common.
Some of these cases should probably be cleaned up in the future not to
do that.
In addition, src/common/nl80211_copy.h and wireless_copy.h were moved
into src/drivers since they are only used by driver wrappers and do not
need to live in src/common.
Instead of using hardcoded maximum A-MPDU length of 64 kB and no
restrictions on minimum MPDU Start Spacing, use the correct values
reported by the driver.
This gets rid of previously deprecated driver_ops handlers set_wpa,
set_drop_unencrypted, set_auth_alg, set_mode. The same functionality
can be achieved by using the init/deinit/associate handlers.
Clean up driver interface by merging hostapd and wpa_supplicant
specific set_beacon driver_ops into a single one. In addition,
merge set_beacon_int into to the same operation.
Current wpa_supplicant has a bug with WEP keys, it adds a zero-length
sequence counter field to netlink which the kernel doesn't accept.
Additionally, the kernel API slightly changed to accept keys only when
connected, so we need to send it the keys after that. For that to work
with shared key authentication, we also include the default WEP TX key
in the authentication command.
To upload the keys properly _after_ associating, add a new flag
WPA_DRIVER_FLAGS_SET_KEYS_AFTER_ASSOC_DONE indicating that the driver
needs the keys at that point and not earlier.
The driver wrappers should not need to include wps_hostapd.h, so let's
make this easier by introducing a driver callback for reporting Probe
Request frames.
None of the driver wrappers user this. hostapd-controlled broadcast SSID
hiding can only be used with drivers that use hostapd for handling
Beacon and Probe Request/Response frames.
None of the driver wrappers use this. Only the drivers that use hostapd
for Beacon and Probe Request/Response handling can now use IEEE 802.11d
properly.
This was not really supported by any of the included driver wrappers. If
this functionality is desired in the future, this (or something similar)
can be added with the changes needed into a driver wrapper to use the
mechanism.
This simplifies driver wrapper operations and removes last direct
struct hostapd_data dereferences from driver_nl80211.c. In addition,
some of the TX callbacks are now fixed for secondary BSSes.
This fixes deauth/disassoc frames in secondary BSSes when using
multi-BSSID. In addition, it reduces need to dereference
struct hostapd_data inside driver wrappers.
Instead of adding a new driver_ops for fetching neighbor BSS data (that
nl80211 driver interface had to scan during initialization), share the
same scan operations that wpa_supplicant is using. This gets rid of
duplicated scan code in driver_nl80211.c (and better yet, removes large
part of old WEXT code).
hostapd interface initialization is now completed in a callback, if
needed, i.e., he_features channel/hw_mode selection can use as much time
as needed. This can also help with radar detection in the future.
Use a parameter structure to pass in information that can be more easily
extended in the future. Include some of the parameters that were
previously read directly from hapd->conf in order to reduce need for
including hostapd/config.h into driver wrappers.
This was not documented properly and was not really used nor would it be
suitable to be used in generic way as it was implemented. It is better
to just remove the parameter since there does not seem to be any
reasonable use for it.
This merges the driver wrapper implementations to use the same
implementation both for hostapd and wpa_supplicant operations to avoid
code duplication.
This commit merges the driver_ops structures and implementations from
hostapd/driver*.[ch] into src/drivers. This is only an initial step and
there is room for number of cleanups to share code between the hostapd
and wpa_supplicant parts of the wrappers to avoid unnecessary source
code duplication.
Need to set WEP keys before requesting authentication in order to get
Shared Key authentication working. Previously, the WEP keys were not set
at all when using SME in wpa_supplicant.
A new network block parameter, scan_freq, can be used to specify subset
of frequencies to scan. This can speed up scanning process considerably
if it is known that only a small subset of channels is actually used in
the network. A union of configured frequencies for all enabled network
blocks is used in scan requests.
Currently, only driver_nl80211.c has support for this functionality.
For example, following parameter marks 2.4 GHz channels 1, 6, 11 to be
scanned: scan_freq=2412 2437 2462
This version is adding the configuration option (mode=2) for this and
driver capability reporting to figure out whether AP mode can be used.
However, this does not actually implement any real functionality yet.
All these driver handlers can be implemented in associate() handler
which gets all the needed information in the parameters structure. The
old functions that provided only a single parameter will be removed
eventually to clean up the driver_ops structure, so driver wrappers
should start using the newer mechanism.
This can be used, e.g., with mac80211-based Linux drivers with
nl80211. This allows over-the-air FT protocol to be used (IEEE
802.11r).
Since the nl80211 interface needed for this is very recent (added
today into wireless-testing.git), driver_nl80211.c has backwards
compatibility code that uses WEXT for association if the kernel does
not support the new commands. This compatibility code can be
disabled by defining NO_WEXT_COMPAT. That code will also be removed
at some point to clean up driver_nl80211.c.
This adds first part of FT resource request as part of Reassocition
Request frame (i.e., FT Protocol, not FT Resource Request Protocol).
wpa_supplicant can generate a test resource request when driver_test.c
is used with internal MLME code and hostapd can verify the FTIE MIC
properly with the included RIC Request.
The actual RIC Request IEs are not processed yet and hostapd does not
yet reply with RIC Response (nor would wpa_supplicant be able to
validate the FTIE MIC for a frame with RIC Response).
Do not use just the driver name for this since driver_ndis.c supports
both wired and wireless NDIS drivers and needs to indicate the driver
type after initialization.
These flags are used to mark which values (level, noise, qual) are
invalid (not available from the driver) and whether level is using dBm.
D-Bus interface will now only report the values that were available.
This can be used to provide support for scanning multiple SSIDs at a
time to optimize scan_ssid=1 operations. In addition, Probe Request IEs
will be available to scan2() (e.g., for WPS PBC scanning).
The driver wrappers can now inform wpa_supplicant how many SSIDs can
be used in a single scan request (i.e., send multiple Probe Requests
per channel). This value is not yet used, but it can eventually be used
to allow a new scan command to specify multiple SSIDs to speed up
scan_ssid=1 operations. In addition, a warning could be printed if
scan_ssid=1 is used with a driver that does not support it
(max_scan_ssids=0).
This commit adds a new build option, CONFIG_IBSS_RSN=y, that can be used
to enable RSN support for IBSS. This links in RSN Authenticator code
from hostapd and adds code for managing per-peer information for IBSS. A
new wpa_cli command or driver event can be used to request RSN
authentication with an IBSS peer. New RSN Authenticator and Supplicant
will be allocated for each peer.
The basic state machine setup code is included in this commit, but the
state machines are not properly started yet. In addition, some of the
callback functions are not yet complete.
The new INTERFACE_LIST global control interface command can be used to
request a list of all available network interfaces that could be used
with the enabled driver wrappers. This could be used to enable
interfaces automatically by external programs (e.g., wpa_gui).
Driver wrappers can now register global_init() and global_deinit()
driver_ops handlers to get a global data structure that can be shared
for all interfaces. This allows driver wrappers to initialize some
functionality (e.g., interface monitoring) before any interfaces have
been initialized.
This adds support for setting of a regulatory domain to wpa_supplicant
drivers. It also adds regulatory domain setting for the nl80211 driver.
We expect an ISO / IEC 3166 alpha2 in the wpa configuration file as a
global.
Fragment WPS IE if needed to fit into the IE length limits in hostapd
and Reassemble WPS IE data from multiple IEs in wpa_supplicant.
In addition, moved WPS code from events.c into wps_supplicant.c to clean
up module interfaces.
This adds WPS support for both hostapd and wpa_supplicant. Both programs
can be configured to act as WPS Enrollee and Registrar. Both PBC and PIN
methods are supported.
Currently, hostapd has more complete configuration option for WPS
parameters and wpa_supplicant configuration style will likely change in
the future. External Registrars are not yet supported in hostapd or
wpa_supplicant. While wpa_supplicant has initial support for acting as
an Registrar to configure an AP, this is still using number of hardcoded
parameters which will need to be made configurable for proper operation.
Find attached the patch that creates a new driver: roboswitch. This
driver adds support for wired authentication with a Broadcom
RoboSwitch chipset. For example it is now possible to do wired
authentication with a Linksys WRT54G router running OpenWRT.
LIMITATIONS
- At the moment the driver does not support the BCM5365 series (though
adding it requires just some register tweaks).
- The driver is also limited to Linux (this is a far more technical
restriction).
- In order to compile against a 2.4 series you need to edit
include/linux/mii.h and change all references to "u16" in "__u16". I
have submitted a patch upstream that will fix this in a future version
of the 2.4 kernel. [These modifications (and more) are now included in
the kernel source and can be found in versions 2.4.37-rc2 and up.]
USAGE
- Usage is similar to the wired driver. Choose the interfacename of
the vlan that contains your desired authentication port on the router.
This name must be formatted as <interface>.<vlan>, which is the
default on all systems I know.
A bug just got reported as a result of this for mac80211 drivers.
https://bugzilla.redhat.com/show_bug.cgi?id=459399
The basic problem is that since taking the device down clears the keys
from the driver on many mac80211-based cards, and since the mode gets
set _after_ the keys have been set in the driver, the keys get cleared
on a mode switch and the resulting association is wrong. The report is
about ad-hoc mode specifically, but this could happen when switching
from adhoc back to managed mode.
