Raspberry pi can't find its AP during iwlist scan

Question

I setup my raspberry pi in AP mode with SSID: rpi-ap-test and my computer can connect to that SSID.

When I do a wifi scan on raspberry pi terminal (iwlist scan), I can see almost APs that my computer can see except rpi-ap-test.

Here is my hostapd.conf file:

interface=wlan0
driver=nl80211
ssid=rpi-ap-test
hw_mode=g
channel=6
macaddr_acl=0
auth_algs=1
ignore_broadcast_ssid=0
wpa=2
wpa_passphrase=xxxxxxxx
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP

I am developing a script that will detect whether raspberry pi in AP mode or not by searching its AP SSID.

Does anyone have any suggestions for me? I am really appreciate.

Answer 1

I think you have to give up hope to find out this way, if your Raspberry Pi is in AP mode or not. It's not even a software questions. It is simply physically not possible.

The results in iwlist scan are populated from scans that are carried out by the wireless chip inside the Raspberry Pi.

• During a passive scan the wireless radio listens for incoming beacon frames from APs in range on the different channels.
• During an active scan the wireless radio sends out probe request frames and waits for probe response frames from APs in range on the different channels.

In both cases the Wifi radio would have to be able to send out the beacon frame/probe response frame (advertising your rpi-ap-test) and listen to it at the same time, which is not possible with a single Wifi radio, as in the Raspberry Pi.

As alternative you could use the output of e.g. iw wlan0 info. Here the field type will report AP, when in AP mode. Replace wlan0 with the name of your wireless interface.