Raspberry Pi Zero W – WiFI AP+Client From Single Built-in WiFi

First update your Pi Zero W to latest Stretch release!

Create or edit your wpa_supplicant configuration:
sudo vi /etc/wpa_supplicant/wpa_supplicant.conf

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
country=GB

network={
    ssid="YOUR_WIFI"
    psk="wifi_password"
    key_mgmt=WPA-PSK
}

Edit the interfaces configuration:
sudo vi /etc/network/interfaces

source-directory /etc/network/interfaces.d

auto lo
auto wlan0
auto wlan1

iface lo inet loopback

allow-hotplug wlan0

iface wlan0 inet dhcp
wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

iface wlan1 inet static
    address 192.168.10.1
    netmask 255.255.255.0
    network 192.168.10.0
    broadcast 192.168.10.255
    gateway 192.168.10.1

Install hostapd and dnsmasq:
sudo apt-get install hostapd dnsmasq

Create a new hostapd configuration:
sudo vi /etc/hostapd/hostapd.conf

The new configuration should look like this, change your wifi ssid and password as your wish:
interface=wlan1
ssid=Pi0W
hw_mode=g
channel=11
macaddr_acl=0
auth_algs=1
ignore_broadcast_ssid=0
wpa=2
wpa_passphrase=new_password
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP

Modify the hostapd default configuration to use your new configuration file:
sudo vi /etc/default/hostapd

Add the following line:
DAEMON_CONF=”/etc/hostapd/hostapd.conf”

Modify the dnsmasq configuration:
sudo vi /etc/dnsmasq.conf

interface=lo,wlan1
no-dhcp-interface=lo,wlan0
bind-interfaces
server=8.8.8.8
domain-needed
bogus-priv
dhcp-range=192.168.10.100,192.168.10.150,12h

Modify sysctl.conf:
sudo vi /etc/sysctl.conf

Uncomment the next line to enable packet forwarding for IPv4:
net.ipv4.ip_forward=1

Modify the rc.local script to run some commands on boot up.
sudo vi /etc/rc.local

Add the following line before “exit 0”.
service dnsmasq start
iptables -t nat -A POSTROUTING -s 192.168.10.0/24 ! -d 192.168.10.0/24 -j MASQUERADE
ifdown wlan0
ifup wlan0

Last step, reboot your Pi Zero W:
sudo reboot

Enjoy your new AP designed by Rasyberry Pi 😀