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There are very many APs.
In my opinion, there are at least 200 APs in this field.

Scanning with iwlist will only scan up to 128 scans.
The debug information of wpa_supplicant is limited to a maximum of 128 scans.
I think the kernel limits the number of scans to 128.

Is there a way to increase this list being scanned?
I would like to see all of the APs in the field without limit.

2 Answers 2

2

I am using wifi as a realtek chip.
The maximum number of ssids at scan time is affected by MAX_BSS_CNT.

The bss_max_count option of wpa_supplicant is only a memory option for wpa_supplicant.

In my realtek kernel device driver, MAX_BSS_CNT was set to 128.
I set MAX_BSS_CNT to 4 and confirmed that only up to 4 scans can be done.

1
Maximum number of BSS entries to keep in memory
Default: 200
This can be used to limit memory use on the BSS entries (cached scan
results). A larger value may be needed in environments that have huge number
of APs when using ap_scan=1 mode.
bss_max_count=200

source: Example wpa_supplicant configuration file


Also, check section ap_scan=n in wpa_supplicant.conf

ap_scan=0 - driver scans the access point.

ap_scan=1 - wpa_supplicant scans the access point, used by default.

ap_scan=2 - like 0, but also takes into account sec. policies and SSID, works with NDISwrapper.


tl;dr

ap_scan — AP scanning/selection

By default, wpa_supplicant requests driver to perform AP scanning and then uses the scan results to select a suitable AP. Another alternative is to allow the driver to take care of AP scanning and selection and use wpa_supplicant just to process EAPOL frames based on IEEE 802.11 association information from the driver.

1: wpa_supplicant initiates scanning and AP selection (default). 0: Driver takes care of scanning, AP selection, and IEEE 802.11 association parameters (e.g., WPA IE generation); this mode can also be used with non-WPA drivers when using IEEE 802.1X mode; do not try to associate with APs (i.e., external program needs to control association). This mode must also be used when using wired Ethernet drivers.

2: like 0, but associate with APs using security policy and SSID (but not BSSID); this can be used, e.g., with ndiswrapper and NDIS drivers to enable operation with hidden SSIDs and optimized roaming; in this mode, the network blocks in the configuration are tried one by one until the driver reports successful association; each network block should have explicit security policy (i.e., only one option in the lists) for key_mgmt, pairwise, group, proto variables.

Note: ap_scan=2 should not be used with the nl80211 driver interface (the current Linux interface). ap_scan=1 is optimized work working with nl80211. For finding networks using hidden SSID, scan_ssid=1 in the network block can be used with nl80211.

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  • also can change DEFAULT_BSS_MAX_COUNT.
    – kangear
    Jun 9, 2019 at 15:23

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