Hardware: Rpi 3 B+

Status: working

As Oct 5 2020 this is working fine with raspbian stretch. Let me know if you have any issue

Raspberry Pi as AccessPoint and Client at the same time!

Rpi3B configuration to use it as WiFi AP and Client simultaneously on the same onboard adapter of the Pi, this also allows the pi to share its internet conection (as a repeater), you can connect to your RPi without the need to be conected to a router nor ethernet, and operate "headless" or "WirelessHead" with the use of ssh or VNC server, having access to the desktop with a tablet or phone with VNC connect

Configure WiFi client

create a copy of /etc/wpa_supplicant/wpa_supplicant.conf in the same folder with the name for your interface e.g interface wlan0 wpa_supplicant-wlan0.conf and set in it the ssid and pass of your router

Install hostapd and dnsmasq

in shell:

sudo apt-get update
sudo apt-get install hostapd dnsmasq

Install rng-tools

sudo apt-get install rng-tools

Set interfaces wlan0 and uap0

In file /etc/network/interfaces Comment all lines except: source-directory /etc/network/interfaces.d Eg.

source-directory /etc/network/interfaces.d
#auto lo
#iface lo inet loopback

#iface eth0 inet manual

#auto wlan0
#allow-hotplug wlan0
#iface wlan0 inet dhcp
#   wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

#allow-hotplug uap0
#auto uap0

or

source-directory /etc/network/interfaces.d
auto lo
auto eth0
auto wlan0

iface lo inet loopback
#iface eth0 inet manual

allow-hotplug wlan0
iface wlan0 inet manual
   wpa-conf /etc/wpa_supplicant/wpa_supplicant-wlan0.conf

Configure static ip in uap0

E.g. Content of /etc/dhcpcd.conf

interface uap0
 static ip_address=192.168.50.1/24

Configure HostAP

Set the name, channel and pass for your raspberry hotspot E.g Content of /etc/hostapd/hostapd.conf

interface=uap0
#driver=nl80211
ssid=PiAP
hw_mode=g
channel=yourAPChannel
wmm_enabled=0
macaddr_acl=0
auth_algs=1
ignore_broadcast_ssid=0
wpa=2
wpa_passphrase=yourPassword
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP

** Set the SSID and password you want the default would be "PiAP" and "yourPassword" respectively, also the channel must be the same to the one you will be connecting the RPi to. (i.e the channel must be the same as your router's)

Configure the daemon for the host AP

Add the following to /etc/default/hostapd

DAEMON_CONF="/etc/hostapd/hostapd.conf"

Configure AP dns

Content of /etc/dnsmasq.conf

interface=lo,uap0
dhcp-range=192.168.50.50,192.168.50.150,12h 

Configure forwarding

Uncomment the next line in /etc/sysctl.conf

net.ipv4.ip_forward=1

Configure Start of services

Add to /etc/rc.local

service hostapd stop
service dnsmasq stop
service dhcpcd stop
iw dev wlan0 interface add uap0 type __ap
iptables -t nat -A POSTROUTING -o wlan0 -j MASQUERADE
service hostapd start
service dnsmasq start
service dhcpcd start

Disable auto start of services

In shell:

sudo systemctl stop hostapd &&
sudo systemctl stop dnsmasq &&
sudo systemctl stop dhcpcd &&
sudo systemctl disable hostapd &&
sudo systemctl disable dnsmasq &&
sudo systemctl disable dhcpcd &&
sudo systemctl start hostapd &&
sudo systemctl start dnsmasq &&
sudo systemctl start dhcpcd

Reboot

sudo reboot

If everything is configured correctly your Pi will be connected to your wifi and also you will see its hotspot network (e.g. PiAP), you will be able to connect to it via any of its two ip (client or hot spot)

Troubleshoot

Problem: hostapd service is masked

Diagnostic command sudo service hostapd status Throws: hostapd service is masked Fix: sudo systemctl unmask hostapd.service

Problem: Not conecting to router

Diagnostic command service dhcpcd status

Throws: uap0: IAID conflicts with one assigned to wlan0

Fix: sudo update-rc.d -f dhcpcd remove

Problem: Not conecting to router

Diagnostic command service hostapd status

Throws: uap0: Could not connect to kernel driver or Not enough entropy pool available for secure operations Fix: install rng-tools (see installation steps)

Other commands

ifup <iface> ifdown <iface>

sudo ifconfig wlan0 up

ip link show