busybox/examples/var_service/supplicant_if/wpa_supplicant.conf

# allow frontend (e.g., wpa_cli) to be used by all users in 'wheel' group
ctrl_interface=DIR=/var/run/wpa_supplicant
#GROUP=wheel

# Typical minimal wifi setup:
network={
    ssid="--your-ESSID--"
    key_mgmt=WPA-PSK
    psk="--your-password--"
}

# Other fields:
#    scan_ssid=1
#    key_mgmt=WPA-EAP WPA-PSK IEEE8021X NONE
#    pairwise=CCMP TKIP
#    group=CCMP TKIP WEP104 WEP40
#    eap=TTLS PEAP TLS
#    identity="user@example.com"
#    password="foobar"
#    ca_cert="/etc/cert/ca.pem"
#    client_cert="/etc/cert/user.pem"
#    private_key="/etc/cert/user.prv"
#    private_key_passwd="password"
#    phase1="peaplabel=0"
#    ca_cert2="/etc/cert/ca2.pem"
#    client_cert2="/etc/cer/user.pem"
#    private_key2="/etc/cer/user.prv"
#    private_key2_passwd="password"