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5 Ancontrol

Name: ancontrol

Configure Aironet 4500/4800 devices.

Synopsis:






ancontrol -i iface -A

ancontrol -i iface -N

ancontrol -i iface -S

ancontrol -i iface -I

ancontrol -i iface -T

ancontrol -i iface -C

ancontrol -i iface -t 0 | 1 | 2 | 3 | 4

ancontrol -i iface -s 0 | 1 | 2 | 3

ancontrol -i iface [-v 1 | 2 | 3 | 4] -a AP

ancontrol -i iface -b beacon_period

ancontrol -i iface [-v 0 | 1] -d 0 | 1 | 2 | 3

ancontrol -i iface -e 0 | 1 | 2 | 3

ancontrol -i iface [-v 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7] -k key

ancontrol -i iface -K 0 | 1 | 2

ancontrol -i iface -W 0 | 1 | 2

ancontrol -i iface -j netjoin_timeout

ancontrol -i iface -l station_name

ancontrol -i iface -m mac_address

ancontrol -i iface [-v 1 | 2 | 3] -n SSID

ancontrol -i iface -o 0 | 1

ancontrol -i iface -p tx_power

ancontrol -i iface -c frequency

ancontrol -i iface -f fragmentation_threshold

ancontrol -i iface -r RTS_threshold

ancontrol -i iface -M 0-15

ancontrol -h


Description: The ancontrol command 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 that 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 ancontrol command 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 ancontrol should be the logical interface name associated with the Aironet device (an0, an1, etc.). If one isn't specified the device an0 will be assumed.

The ancontrol command is not designed to support the combination of arguments from different SYNOPSIS lines in a single ancontrol invocation, and such combinations are not recommended.

Parameters

-i iface -A

Displays 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 that serves the SSID(s) specified in the SSID list. The AP list can be modified with the -a option.

-i iface -N

Displays 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

Displays 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 "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

Displays NIC capability information. This shows the device type, frequency, speed, and power level capabilities and firmware revision levels.

-i iface -T

Displays the NIC's internal statistics counters.

-i iface -C

Displays 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 -t 0 | 1 | 2 | 3 | 4

Selects transmit speed. The available settings are as follows:

TX rate

NIC speed

0

AutoŚNIC selects optimal speed

1

1 Mbps fixed

2

2 Mbps fixed

3

5.5 Mbps fixed

4

11 Mbps fixed


Note that the 5.5 and 11 Mbps settings are only supported on the 4800 series adapters; the 4500 series adapters have a maximum speed of 2 Mbps.

-i iface -s 0 | 1 | 2 | 3

Sets power save mode. Valid selections are as follows:

Selection

Power save mode

0

None; power save disabled

1

Constantly awake mode (CAM)

2

Power Save Polling (PSP)

3

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 nonzero.

-i iface [-v 1 | 2 | 3 | 4] -a AP

Sets 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 100 ms.

-i iface [-v 0 | 1] -d 0 | 1 | 2 | 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:

Selection

Diversity

0

Select factory default diversity

1

Antenna 1 only

2

Antenna 2 only

3

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 | 1 | 2 | 3

Sets 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.

-i iface [-v 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7] -k key

Sets a WEP key. For 40-bit prefix 10 hex character with 0x. For 128-bit prefix 26 hex character with 0x. Use "" as the key to erase the key. Supports 4 keys; even numbers are for permanent keys and odd numbers 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.

-i iface -K 0 | 1 | 2

Sets authorization type. Use 0 for none, 1 for Open, and 2 for Shared Key.

-i iface -W 0 | 1 | 2

Enables WEP. Use 0 for no WEP, 1 to enable full WEP, and 2 for mixed cell.

-i iface -j netjoin_timeout

Sets 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

Sets 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

Sets 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 | 2 | 3] -n SSID

Sets 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 isn't used, the first SSID in the list is set.

-i iface -o 0 | 1

Sets 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

Sets 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

Sets the radio frequency of a given interface. The frequency should be specified as a channel ID as shown in the following list. 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 ID

FCC

ETSI

France

Japan

1

2412

2412

-

-

2

2417

2417

-

-

3

2422

2422

-

-

4

2427

2427

-

-

5

2432

2432

-

-

6

2437

2437

-

-

7

2442

2442

-

-

8

2447

2447

-

-

9

2452

2452

-

-

10

2457

2457

2457

-

11

2462

2462

2462

-

12

-

2467

2467

-

13

-

2472

2472

-

14

-

-

-

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 to communicate.

-i iface -f fragmentation_threshold

Sets 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

Sets 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

Sets 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 an SSID must be set.


-h

Prints 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 vunerable 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 counterintuitive, 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.

Examples:






ancontrol -i an0 -v 0 -k 0x12345678901234567890123456

ancontrol -i an0 -K 2

ancontrol -i an0 -W 1

ancontrol -i an0 -e 0


Sets a WEP key 0, enables "Shared Key"' authentication, enables full WEP and uses transmit key 0.

See also: an(4), ifconfig(8)

History: The ancontrol command first appeared in FreeBSD 4.0.

Bugs: 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.

Author: Bill Paul (wpaul@ee.edu)

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