___        ___________
|   | eth0 |           | wlan0(Accesspoint)
|box|-----<Eth        USB1>EdimaxWlanStick <<<<<<  PC/Laptop/Smartphone
|___|      | Raspberry |
           | Pi        | wlan1(Connection to Router for Internet)
           |          USB2>EdimaxWlanStick >>>>>>  Router >>>> Internet
           |___________|

auto eth0
iface eth0 inet static
    address 192.168.101.1
    netmask 255.255.255.0

auto wlan0
iface wlan0 inet static
    address 192.168.102.1
    netmask 255.255.255.0

auto wlan1
iface wlan1 inet dhcp
wpa-conf /etc/wpa.conf

auto br0
iface br0 inet static
bridge_ports eth0 wlan0
address 192.168.100.1
netmask 255.255.255.0

interface=wlan0
ssid=Blackbox
channel=10
driver=rtl871xdrv
ieee80211n=1
hw_mode=g
device_name=RTL8188CUS
manufacturer=Realtek
wpa=2
wpa_passphrase=********Secret
wpa_key_mgmt=WPA-PSK
wpa_pairwise=CCMP
rsn_pairwise=CCMP

# Other settings
beacon_int=100
auth_algs=3
wmm_enabled=1

auto eth0
iface eth0 inet dhcp

auto wlan0
iface wlan0 inet dhcp

auto wlan1
iface wlan1 inet dhcp
wpa-conf /etc/wpa.conf

auto br0
iface br0 inet dhcp
bridge_ports eth0 wlan0 wlan1

sudo echo 1 > /proc/sys/net/ipv4/ip_forward
sudo iptables -t nat -A POSTROUTING -o wlan1 -s 192.168.100.0/24 -j MASQUERADE