Enabling Simultaneous AP and Managed Mode WiFi on Raspberry Pi (Raspbian Stretch)

install.sh

#!/bin/bash
#see: https://albeec13.github.io/2017/09/26/raspberry-pi-zero-w-simultaneous-ap-and-managed-mode-wifi/

x="/etc/udev/rules.d/70-persistent-net.rules"

cat < "$x" <<- EOL
SUBSYSTEM=="ieee80211", ACTION=="add|change", ATTR{macaddress}=="b8:27:eb:ff:ff:ff", KERNEL=="phy0", \
  RUN+="/sbin/iw phy phy0 interface add ap0 type __ap", \
  RUN+="/bin/ip link set ap0 address b8:27:eb:ff:ff:ff"
EOL

sudo apt install -y dnsmasq hostapd

x="/etc/dnsmasq.conf"

cat < "$x" <<- EOL
interface=lo,ap0
no-dhcp-interface=lo,wlan0
bind-interfaces
server=8.8.8.8
domain-needed
bogus-priv
dhcp-range=192.168.10.50,192.168.10.150,12h
EOL

echo "Type a 1-32 character SSID (name) for your network, then press [ENTER]:"
read ssid

pwd1="0"
pwd2="1"

until [ $pwd1 == $pwd2 ]; do 
  echo "Type a password to access your network, then press [ENTER]:"
  read -s pwd1
  echo "Verify password to access your network, then press [ENTER]:"
  read -s pwd2
done
 
if [ $pwd1 == $pwd2 ]; then
  echo "Password set. Edit $x to change."
fi

x="/etc/hostapd/hostapd.conf"

cat < "$x" <<- EOL
ctrl_interface=/var/run/hostapd
ctrl_interface_group=0
interface=ap0
driver=nl80211
ssid=$ssid
hw_mode=g
channel=11
wmm_enabled=0
macaddr_acl=0
auth_algs=1
wpa=2
wpa_passphrase=$pwd1
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP CCMP
rsn_pairwise=CCMP
EOL

#see: https://askubuntu.com/a/832592/552275
iw dev wlan0 scan | egrep "signal|SSID" | sed -e "s/\tsignal: //" -e "s/\tSSID: //" | awk '{ORS = (NR % 2 == 0)? "\n" : " "; print} | sort

echo "Type the 1-32 character SSID (name) of the network you choose, then press [ENTER]:
read SSID

echo "Type a password to access your choosen network, then press [ENTER]:"
read -s PSK

x="/etc/default/hostapd"

cat < "$x" <<- EOL
DAEMON_CONF="/etc/hostapd/hostapd.conf"
EOL

x="/etc/wpa_supplicant/wpa_supplicant.conf"

cat < "$x" <<- EOL
country=US
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1

network={
    ssid="$SSID"
    psk="$PSK"
    id_str="AP"
}
EOL

x="/etc/network/interfaces"
cp "$x" "$x".bak

cat < "$x" <<- EOL
# interfaces(5) file used by ifup(8) and ifdown(8)

# Please note that this file is written to be used with dhcpcd
# For static IP, consult /etc/dhcpcd.conf and 'man dhcpcd.conf'

# Include files from /etc/network/interfaces.d:
source-directory /etc/network/interfaces.d

auto lo
auto ap0
auto wlan0
iface lo inet loopback

allow-hotplug ap0
iface ap0 inet static
    address 192.168.10.1
    netmask 255.255.255.0
    hostapd /etc/hostapd/hostapd.conf

allow-hotplug wlan0
iface wlan0 inet manual
    wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf
iface AP inet dhcp
EOL

x="/usr/local/bin/start-ap-managed-wifi.sh"

cat < "$x" <<- EOL
#!/bin/bash
sleep 30
sudo ifdown --force wlan0 && sudo ifdown --force ap0 && sudo ifup ap0 && sudo ifup wlan0
sudo sysctl -w net.ipv4.ip_forward=1
sudo iptables -t nat -A POSTROUTING -s 192.168.10.0/24 ! -d 192.168.10.0/24 -j MASQUERADE
sudo systemctl restart dnsmasq
EOL

sudo chmod +x "$x"

(crontab -l 2>/dev/null; @reboot "$x") | crontab -

there's a missing ' and " in lines 64 and 66 respectively

unfortunately I could not make this work. Might be due to the use of /etc/network/interfaces, which has been recently replaced by dhcpcd.conf

have you tried in most recent version of raspbian and RPi3+?

This is the procedure for the newer systemd based Raspbian/Raspberry OS versions.

https://raspberrypi.stackexchange.com/questions/89803/access-point-as-wifi-router-repeater-optional-with-bridge/89804#89804