Starting an environment scan at a configurable time

Your WLAN's environment can be regularly searched for rogue APs.

You can configure the times of the automatic environment scan for rogue APs.

Environment scans should be performed at times that minimize interference to normal operations.

This feature allows you to perform the scan of the configured frequency band each day at a predefined time.

In this case, scan refers to:

Active scanning using probe requests.
Passive scanning for beacons.

Note: It is not always possible to use active scanning, for example where a 5-GHz channel is not DFS-free. No transmissions are permitted in this case.

The configuration is performed from the command console, shown here with default values as an example:

root@LN-1700Esc:/Setup/Interfaces/WLAN/Environment-Scan 
> ls -a

[1.3.6.1.4.1.2356.11][2.23.20.27]
Ifc      Operating  Hour    Minute  Channel-List
[1]      [2]         [3]    [4]     [5]
=========------------------------------------------------------------------
WLAN-1    No          3      0
WLAN-2    No          3      0

"Hour" and "Minute" are used to set the time at which the daily environment scan is performed. These fields also permit the use of the CRON syntax. The channel list can be used to limit the channels to be scanned (as a comma-separated list). If this list is left empty, all of the channels of the frequency band operating on the module are scanned.

During the scan, the WLAN module spends about three seconds on each channel. The next channel is then scanned. Once all of the configured channels have been scanned, the module returns to normal operating mode.

Note: During the scan the module is not capable of regular WLAN operations, in contrast, for example, to the background scan. However, only one of the two modules can perform an environment scan at any one time, and the other module operates normally.

In addition to the time-controlled activation of the environment scan, it can also be activated permanently. For this purpose, the WLAN module can be switched to the operating mode "Scanner" (see operation mode 7):

root@LN-1700Esc:/Setup/Interfaces/WLAN/Operational
> l

Ifc       Operating     Operation-Mode  Link-LED-Function     Broken-Link-Detection
==========--------------------------------------------------------------------------
WLAN-1    Yes           Scanner         Normal                No
WLAN-2    Yes           managed-AP      Normal                No

root@LN-1700Esc:/Setup/Interfaces/WLAN/Operational
> set ?

Possible input for columns in table 'Operational':
[  1] Ifc                   : WLAN-1 (1), WLAN-2 (2)
[  2] Operating             : Yes (0), No (1)
[  3] Operation-Mode        : Access-Point (1), managed-AP (4), Station (0), 
                              Probe (5), Scanner (7)
[  4] Link-LED-Function     : Normal (0), Client-Mode-Strength (1), P2P-1-Strength (8))
[  5] Broken-Link-Detection : No (0), LAN-1 (1), LAN-2 (2)

This performs the environment scan as described above: After scanning the configured channels, the scan does not terminate but it starts again from the beginning.

This operating mode allows the use of an AP as a full-time "scanner" AP.

The result of the environment scan can be found in the table Status > WLAN > Environment-Scan-Results.

See Environment scan for the configuration in LANconfig.