How to Setup a Wireless Access Point on the Raspberry Pi

In this quick guide we will show you how to setup and configure a wireless access point on the Raspberry Pi. There are many reasons why you may want to do this, in our case we wanted to access a local webpage stored on the Pi which controlled certain GPIO pins. You may want to access media files or other functionalities of your Pi, in which case this is the guide for you. The following guide has been adapted and inspired by the Raspberry Pi foundation.

What you need

All you need for this project is a Raspberry Pi with built-in Wi-Fi or using a USB wireless adaptor. We will be using the latest software version of Raspbian and can bu used on the full Desktop version or the Lite version of Buster. If you need to purchase a Raspberry Pi or accessories then please visit Pi-Supply.com .

Getting Started

First make sure you download the latest version of Raspbian OS from https://www.raspberrypi.org/downloads/and the flash it to an SD card.

The follow instructions will show you how to setup an access point in a standalone network to operate on its own without external access from the internet. If you require the access point to be bridge with an already existing network then please see this guide here – https://www.raspberrypi.org/documentation/configuration/wireless/access-point.md#internet-sharing

In order to work as an access point, the Raspberry Pi will need to have access point software installed, along with DHCP server software to provide connecting devices with a network address.

To create an access point, we’ll need DNSMasq and HostAPD. Install all the required software in one go with this command:

sudo apt install dnsmasq hostapd

Since the configuration files are not ready yet, turn the new software off as follows:

sudo systemctl stop dnsmasq
sudo systemctl stop hostapd

Configuring a static IP

We are configuring a standalone network to act as a server, so the Raspberry Pi needs to have a static IP address assigned to the wireless port. This documentation assumes that we are using the standard 192.168.x.x IP addresses for our wireless network, so we will assign the server the IP address 192.168.4.1. It is also assumed that the wireless device being used is wlan0.

To configure the static IP address, edit the dhcpcd configuration file with:

sudo nano /etc/dhcpcd.conf

Go to the end of the file and edit it so that it looks like the following:

interface wlan0
    static ip_address=192.168.4.1/24
    nohook wpa_supplicant

Now restart the dhcpcd daemon and set up the new wlan0 configuration:

sudo service dhcpcd restart

Configuring the DHCP server (dnsmasq)

The DHCP service is provided by dnsmasq. By default, the configuration file contains a lot of information that is not needed, and it is easier to start from scratch. Rename this configuration file, and edit a new one:

sudo mv /etc/dnsmasq.conf /etc/dnsmasq.conf.orig
sudo nano /etc/dnsmasq.conf

Type or copy the following information into the dnsmasq configuration file and save it:

interface=wlan0      # Use the require wireless interface - usually wlan0
dhcp-range=192.168.4.2,192.168.4.20,255.255.255.0,24h

So for wlan0, we are going to provide IP addresses between 192.168.4.2 and 192.168.4.20, with a lease time of 24 hours. If you are providing DHCP services for other network devices (e.g. eth0), you could add more sections with the appropriate interface header, with the range of addresses you intend to provide to that interface.

Start dnsmasq (it was stopped), it will now use the updated configuration:

sudo systemctl start dnsmasq

Configuring the access point host software (hostapd)

You need to edit the hostapd configuration file, located at /etc/hostapd/hostapd.conf, to add the various parameters for your wireless network. After initial install, this will be a new/empty file.

sudo nano /etc/hostapd/hostapd.conf

Add the information below to the configuration file. This configuration assumes we are using channel 7, with a network name of NameOfNetwork, and a password AardvarkBadgerHedgehog. Note that the name and password should not have quotes around them. The passphrase should be between 8 and 64 characters in length.

To use the 5 GHz band, you can change the operations mode from hw_mode=g to hw_mode=a. Possible values for hw_mode are:

• a = IEEE 802.11a (5 GHz)
• b = IEEE 802.11b (2.4 GHz)
• g = IEEE 802.11g (2.4 GHz)
• ad = IEEE 802.11ad (60 GHz) (Not available on the Raspberry Pi)

interface=wlan0
driver=nl80211
ssid=NameOfNetwork
hw_mode=g
channel=7
wmm_enabled=0
macaddr_acl=0
auth_algs=1
ignore_broadcast_ssid=0
wpa=2
wpa_passphrase=AardvarkBadgerHedgehog
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP

We now need to tell the system where to find this configuration file.

sudo nano /etc/default/hostapd

Find the line with #DAEMON_CONF, and replace it with this:

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

Start it up

Now enable and start hostapd:

sudo systemctl unmask hostapd
sudo systemctl enable hostapd
sudo systemctl start hostapd

Do a quick check of their status to ensure they are active and running:

sudo systemctl status hostapd
sudo systemctl status dnsmasq

Add routing and masquerade

Edit /etc/sysctl.conf and uncomment this line:

net.ipv4.ip_forward=1

Add a masquerade for outbound traffic on eth0:

sudo iptables -t nat -A  POSTROUTING -o eth0 -j MASQUERADE

Save the iptables rule.

sudo sh -c "iptables-save > /etc/iptables.ipv4.nat"

Edit /etc/rc.local and add this just above “exit 0” to install these rules on boot.

iptables-restore < /etc/iptables.ipv4.nat

Reboot.

Once rebooted, if you go to another device that has wireless and search for wireless networks you should be able to see your wireless access point and be able to connect to it using the credentials that you configured.