The
utility controls the operation of Aironet wireless networking
devices via the
an(4)
driver.
Most of the parameters that can be changed relate to the
IEEE 802.11 protocol which the Aironet cards implement.
This includes such things as
the station name, whether the station is operating in ad-hoc (point
to point) or infrastructure mode, and the network name of a service
set to join.
The
utility can also be used to view the current NIC status, configuration
and to dump out the values of the card's statistics counters.
The
iface
argument given to
should be the logical interface name associated with the Aironet
device
( an0 , an1
etc.).
If one is not specified the device
``an0
''
will be assumed.
The
utility is not designed to support the combination of arguments from different
Sx SYNOPSIS
lines in a single
invocation, and such combinations are not recommended.
OPTIONS
The options are as follows:
-i iface -A
Display the preferred access point list.
The AP list can be used by
stations to specify the MAC address of access points with which it
wishes to associate.
If no AP list is specified (the default) then
the station will associate with the first access point that it finds
which serves the SSID(s) specified in the SSID list.
The AP list can
be modified with the
-a
option.
-i iface -N
Display the SSID list.
This is a list of service set IDs (i.e., network names)
with which the station wishes to associate.
There may be up to three SSIDs
in the list: the station will go through the list in ascending order and
associate with the first matching SSID that it finds.
-i iface -S
Display NIC status information.
This includes the current operating
status, current BSSID, SSID, channel, beacon period and currently
associated access point.
The operating mode indicates the state of
the NIC, MAC status and receiver status.
When the
Qq Li synced
keyword
appears, it means the NIC has successfully associated with an access
point, associated with an ad-hoc
``master''
station, or become a
``master''
itself.
The beacon period can be anything between 20 and 976 milliseconds.
The default is 100.
-i iface -I
Display NIC capability information.
This shows the device type,
frequency, speed and power level capabilities and firmware revision levels.
-i iface -T
Display the NIC's internal statistics counters.
-i iface -C
Display current NIC configuration.
This shows the current operation mode,
receive mode, MAC address, power save settings, various timing settings,
channel selection, diversity, transmit power and transmit speed.
-i iface -Q
Display the cached signal strength information maintained by the
an(4)
driver.
The driver retains information about signal strength and
noise level for packets received from different hosts.
The signal strength and noise level values are displayed in units of dBms by
default.
The
hw.an.an_cache_modesysctl(8)
variable can be set to
raw , dbm
or
per
-i iface -Z
Clear the signal strength cache maintained internally by the
an(4)
driver.
-i iface -R
Display RSSI map that converts from the RSSI index to percent and dBm.
-i iface -t 0 - 4
Select transmit speed.
The available settings are as follows:
TX rateNIC speed
0 Ta Auto -- NIC selects optimal speed
1 Ta 1Mbps fixed
2 Ta 2Mbps fixed
3 Ta 5.5Mbps fixed
4 Ta 11Mbps fixed
Note that the 5.5 and 11Mbps settings are only supported on the 4800
series adapters: the 4500 series adapters have a maximum speed of 2Mbps.
-i iface -s 0 - 3
Set power save mode.
Valid selections are as follows:
SelectionPower save mode
0 Ta None - power save disabled
1 Ta Constantly awake mode (CAM)
2 Ta Power Save Polling (PSP)
3 Ta Fast Power Save Polling (PSP-CAM)
Note that for IBSS (ad-hoc) mode, only PSP mode is supported, and only
if the ATIM window is non-zero.
-i iface [-v 1 - 4 -a AP
]
Set preferred access point.
The
AP
is specified as a MAC address consisting of 6 hexadecimal values
separated by colons.
By default, the
-a
option only sets the first entry in the AP list.
The
-v
modifier can be used to specify exactly which AP list entry is to be
modified.
If the
-v
flag is not used, the first AP list entry will be changed.
-i iface -b beacon_period
Set the ad-hoc mode beacon period.
The
beacon_period
is specified in milliseconds.
The default is 100ms.
-i iface [-v 0 | 1 -d 0 - 3
]
Select the antenna diversity.
Aironet devices can be configured with up
to two antennas, and transmit and receive diversity can be configured
accordingly.
Valid selections are as follows:
SelectionDiversity
0 Ta Select factory default diversity
1 Ta Antenna 1 only
2 Ta Antenna 2 only
3 Ta Antenna 1 and 2
The receive and transmit diversity can be set independently.
The user
must specify which diversity setting is to be modified by using the
-v
option: selection
0
sets the receive diversity and
1
sets the transmit diversity.
-i iface -e 0 - 4
Set the transmit WEP key to use.
Note that until this command is issued, the device will use the
last key programmed.
The transmit key is stored in NVRAM.
Currently
set transmit key can be checked via
-C
option.
Selection
4
sets the card in
``Home Network Mode''
and uses the home key.
-i iface [-v 0 - 8 -k key
]
Set a WEP key.
For 40 bit prefix 10 hex character with 0x.
For 128 bit prefix 26 hex character with 0x.
Use
Qq as the key to erase the key.
Supports 4 keys; even numbers are for permanent keys
and odd number are for temporary keys.
For example,
-v 1
sets the first temporary key.
(A
``permanent''
key is stored in NVRAM; a
``temporary''
key is not.)
Note that the device will use the most recently-programmed key by default.
Currently set keys can be checked via
-C
option, only the sizes of the
keys are returned.
The value of
8
is for the home key.
Note that the value for the home key can be read back from firmware.
-i iface -K 0 - 2
Set authorization type.
Use
0
for none,
1
for
``Open''
2
for
``Shared Key''
-i iface -W 0 - 2
Enable WEP.
Use
0
for no WEP,
1
to enable full WEP,
2
for mixed cell.
-i iface -L user_name
Enable LEAP and query for password.
It will check to see if it has authenticated for up to 60s.
To disable LEAP, set WEP mode.
-i iface -j netjoin_timeout
Set the ad-hoc network join timeout.
When a station is first activated
in ad-hoc mode, it will search out a
``master''
station with the desired
SSID and associate with it.
If the station is unable to locate another
station with the same SSID after a suitable timeout, it sets itself up
as the
``master''
so that other stations may associate with it.
This
timeout defaults to 10000 milliseconds (10 seconds) but may be changed
with this option.
The timeout should be specified in milliseconds.
-i iface -l station_name
Set the station name used internally by the NIC.
The
station_name
can be any text string up to 16 characters in length.
The default name
is set by the driver to
``FreeBSD
''
-i iface -m mac_address
Set the station address for the specified interface.
The
mac_address
is specified as a series of six hexadecimal values separated by colons,
e.g.:
00:60:1d:12:34:56
This programs the new address into the card
and updates the interface as well.
-i iface [-v 1 - 3 -n SSID
]
Set the desired SSID (network name).
There are three SSIDs which allows
the NIC to work with access points at several locations without needing
to be reconfigured.
The NIC checks each SSID in sequence when searching
for a match.
The SSID to be changed can be specified with the
-v
modifier option.
If the
-v
flag is not used, the first SSID in the list is set.
-i iface -o 0 | 1
Set the operating mode of the Aironet interface.
Valid selections are
0
for ad-hoc mode and
1
for infrastructure mode.
The default driver setting is for infrastructure
mode.
-i iface -p tx_power
Set the transmit power level in milliwatts.
Valid power settings
vary depending on the actual NIC and can be viewed by dumping the
device capabilities with the
-I
flag.
Typical values are 1, 5, 20, 50 and 100mW.
Selecting 0 sets
the factory default.
-i iface -c frequency
Set the radio frequency of a given interface.
The
frequency
should be specified as a channel ID as shown in the table below.
The
list of available frequencies is dependent on radio regulations specified
by regional authorities.
Recognized regulatory authorities include
the FCC (United States), ETSI (Europe), France and Japan.
Frequencies
in the table are specified in MHz.
Channel IDFCCETSIFranceJapan
1 Ta 2412 Ta 2412 Ta - Ta -
2 Ta 2417 Ta 2417 Ta - Ta -
3 Ta 2422 Ta 2422 Ta - Ta -
4 Ta 2427 Ta 2427 Ta - Ta -
5 Ta 2432 Ta 2432 Ta - Ta -
6 Ta 2437 Ta 2437 Ta - Ta -
7 Ta 2442 Ta 2442 Ta - Ta -
8 Ta 2447 Ta 2447 Ta - Ta -
9 Ta 2452 Ta 2452 Ta - Ta -
10 Ta 2457 Ta 2457 Ta 2457 Ta -
11 Ta 2462 Ta 2462 Ta 2462 Ta -
12 Ta - Ta 2467 Ta 2467 Ta -
13 Ta - Ta 2472 Ta 2472 Ta -
14 Ta - Ta - Ta - Ta 2484
If an illegal channel is specified, the
NIC will revert to its default channel.
For NICs sold in the United States
and Europe, the default channel is 3.
For NICs sold in France, the default
channel is 11.
For NICs sold in Japan, the only available channel is 14.
Note that two stations must be set to the same channel in order to
communicate.
-i iface -f fragmentation_threshold
Set the fragmentation threshold in bytes.
This threshold controls the
point at which outgoing packets will be split into multiple fragments.
If a single fragment is not sent successfully, only that fragment will
need to be retransmitted instead of the whole packet.
The fragmentation
threshold can be anything from 64 to 2312 bytes.
The default is 2312.
-i iface -r RTS_threshold
Set the RTS/CTS threshold for a given interface.
This controls the
number of bytes used for the RTS/CTS handshake boundary.
The
RTS_threshold
can be any value between 0 and 2312.
The default is 2312.
-i iface -M 0 - 15
Set monitor mode via bit mask, meaning:
Bit
Meaning
0
to not dump 802.11 packet.
1
to enable 802.11 monitor.
2
to monitor any SSID.
4
to not skip beacons, monitor beacons produces a high system load.
8
to enable full Aironet header returned via BPF.
Note it appears that a SSID must be set.
-h
Print a list of available options and sample usage.
SECURITY NOTES
WEP
(``wired equivalent privacy''
)
is based on the RC4 algorithm,
using a 24 bit initialization vector.
RC4 is supposedly vulnerable to certain known plaintext attacks,
especially with 40 bit keys.
So the security of WEP in part depends on how much known plaintext
is transmitted.
Because of this, although counter-intuitive, using
``shared key''
authentication (which involves sending known plaintext) is less
secure than using
``open''
authentication when WEP is enabled.
Devices may alternate among all of the configured WEP keys when
transmitting packets.
Therefore, all configured keys (up to four) must agree.
The statistics counters do not seem to show the amount of transmit
and received frames as increasing.
This is likely due to the fact that
the
an(4)
driver uses unmodified packet mode instead of letting the NIC perform
802.11/ethernet encapsulation itself.
Setting the channel does not seem to have any effect.
