Setting up your RPi as a WiFi access point
Configuring Raspberry Pi 3 WiFi As An Access Point
The below is based on this excellent guide here on the Frillips blog: https://frillip.com/using-your-raspberry-pi-3-as-a-wifi-access-point-with-hostapd/
You should follow that guide, we’ve just duplicated here for our needs in case it ever vanishes.
Installing The Required Packages
Let you to use the built in WiFi as an access point.
A combined DHCP and DNS server that’s easy to configure (less heavyweight than isc-dhcp-server and bind9)
sudo apt-get install dnsmasq hostapd
Configuring Raspbian DHCP
In Raspian interface configuration is handled by dhcpcd. We need to tell it to ignore wlan0, as we will be configuring it with a static IP address elsewhere.
Open up the dhcpcd configuration file:
sudo nano /etc/dhcpcd.conf
Add the following to the bottom of the file (but above any interface lines you may have added):
#DISABLE WLAN0 FROM DHCPCD AS WE ARE USING IT AS A WIFI ACCESS POINT denyinterfaces wlan0
Set WLAN0 static IP Address
Open up the interface configuration file:
sudo nano /etc/network/interfaces
Edit the wlan0 section so that it looks like this:
allow-hotplug wlan0 iface wlan0 inet static wireless-mode Master address 192.168.0.1 netmask 255.255.255.0 network 192.168.0.0 broadcast 192.168.0.255 # wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf
N.B. Make sure the subnet is different from the subnet you are using on your eth0 connection if you are connecting via SSH, otherwise you’ll loose your connection on eth0!!
Restart dhcpcd and then reload the configuration for wlan0 with:
sudo service dhcpcd restart sudo ifdown wlan0; sudo ifup wlan0
Create a new configuration file:
sudo nano /etc/hostapd/hostapd.conf
Copy this into the file:
interface=wlan0 # Use the nl80211 driver with the brcmfmac driver driver=nl80211 # The name to use for the network ssid=RPi-AP # Use the 2.4GHz band hw_mode=g # Use channel 6 channel=6 # Enable 802.11n ieee80211n=1 # Enable WMM wmm_enabled=1 # Enable 40MHz channels with 20ns guard interval ht_capab=[HT40][SHORT-GI-20][DSSS_CCK-40] # Accept all MAC addresses macaddr_acl=0 # Use WPA authentication auth_algs=1 # Broadcast the network name ignore_broadcast_ssid=0 # Use WPA2 wpa=2 # Use a pre-shared key wpa_key_mgmt=WPA-PSK # The WPA2 passphrase (password) wpa_passphrase=raspberry # Use AES, instead of TKIP rsn_pairwise=CCMP
Save and exit.
To verify its working by entering this and checking you see network “RPi3-AP”
sudo /usr/sbin/hostapd /etc/hostapd/hostapd.conf
Use Ctrl+C to stop it.
If you tried connecting to it, you would see some output from the Pi, but you won’t receive an IP address until dnsmasq is set up.
We need to tell hostapd where to look for the config file when it starts up on boot. Open up the default configuration file:
sudo nano /etc/default/hostapd
find the line
and replace it with:
Note: “_CONF”, NOT “#DAEMON_OPTS”!!! REMOVE THE ‘#’ AT THE START OF THE LINE!!!!
The default dnsmasq config file contains lots of information on how to use it, but the majority of it is largely redundant for our purposes. So to simplify things we move it and then create a new one:
sudo mv /etc/dnsmasq.conf /etc/dnsmasq.conf.orig sudo nano /etc/dnsmasq.conf
Copy in the following:
# Use interface wlan0 interface=wlan0 # Explicitly specify the address to listen on listen-address=192.168.0.1 # Bind to the interface to make sure we aren't sending things elsewhere bind-interfaces # Forward DNS requests to Google DNS server=188.8.131.52 # Don't forward short names domain-needed # Never forward addresses in the non-routed address spaces. bogus-priv # Assign IP addresses between 192.168.0.5 and 192.168.0.250 with a 12 hour lease time dhcp-range=192.168.0.5,192.168.0.250,12h
Set Up IPv4 Forwarding
We need to enable packet forwarding. Open up the sysctl.conf file:
sudo nano /etc/sysctl.conf
Remove the # from the beginning of the line containing:
Save and exit. This will enable it on the next reboot. You can activate it immediately with:
sudo sh -c "echo 1 > /proc/sys/net/ipv4/ip_forward"
To share our eth0 internet connection to devices connected over WiFi we need to configure a NAT between our wlan0 interface and our eth0 interface. Use the following commands:
sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE sudo iptables -A FORWARD -i eth0 -o wlan0 -m state --state RELATED,ESTABLISHED -j ACCEPT sudo iptables -A FORWARD -i wlan0 -o eth0 -j ACCEPT
We need these rules to be applied every time we reboot so run:
sudo sh -c "iptables-save > /etc/iptables.ipv4.nat"
to save the rules to the file /etc/iptables.ipv4.nat. We need to run this after each reboot, so open the rc.local file with:
sudo nano /etc/rc.local
Just above the line exit 0, add the following:
# Special for using wlan0 as an access point iptables-restore < /etc/iptables.ipv4.nat
Start The Services
sudo service hostapd start sudo service dnsmasq start
You should now see a new WiFi network with SSID “RPi-AP”
WiFi access point DHCP server no longer working
Issue encountered after updating all packages on Raspbian Jesse
Can connect to the WiFi access point but when I look at the IP settings of my computer the DHCP server on the RPi has not functioned and issued correct settings. Using the command “service dnsmasq status” I get this:
● dnsmasq.service - dnsmasq - A lightweight DHCP and caching DNS server Loaded: loaded (/lib/systemd/system/dnsmasq.service; enabled) Drop-In: /run/systemd/generator/dnsmasq.service.d └─50-dnsmasq-$named.conf, 50-insserv.conf-$named.conf Active: failed (Result: exit-code) since Wed 2019-05-08 08:28:20 UTC; 11h ago Process: 705 ExecStart=/etc/init.d/dnsmasq systemd-exec (code=exited, status=1/FAILURE) Process: 657 ExecStartPre=/usr/sbin/dnsmasq --test (code=exited, status=0/SUCCESS) pi@raspberrypi:~ $
Solution found on this page
is to issue the following command to remove dns-root-data:
sudo apt-get --purge remove dns-root-data