Open Network

Config File

open.conf:

network={
    ssid="NETWORK-NAME"
    key_mgmt=NONE
}

For hidden SSIDs, add scan_ssid=1:

network={
    ssid="NETWORK-NAME"
    key_mgmt=NONE
    scan_ssid=1
}

sudo wpa_supplicant -Dnl80211 -i <INTERFACE> -c open.conf

Get an IP address:

sudo dhclient <INTERFACE> -v