Você precisa usar o scan_ssid para se conectar a SSIDs ocultos.
Na sua configuração, será:
auto wlan0
iface wlan0 inet dhcp
wpa-ssid MySSID
wpa-psk myHashedPSK
wpa-scan-ssid 1
Em wpa_supplicant.conf , é:
network={
ssid="MySSID"
scan_ssid=1
psk=myHashedPSK
}
Deve ser suficiente configurar as propriedades SSID em /etc/network/interfaces ou /etc/wpa_supplicant/wpa_supplicant.conf .
De wpa_supplicant.conf manual:
scan_ssid: SSID scan technique; 0 (default) or 1. Technique 0 scans for the SSID using a broadcast Probe Request frame while 1 uses a directed Probe Request frame. Access points that cloak themselves by not broadcasting their SSID require technique 1, but beware that this scheme can cause scanning to take longer to complete.