The Raspberry Pi can be used as a bridged wireless access point within an existing ethernet network. This will extend the network to wireless computers and devices.
If you wish to create a wireless network that could function stand-alone, consider instead setting up a routed access point.
+- RPi -------+
+---+ Bridge |
| | WiFi AP +-)))
| | 192.168.1.2 | +- Laptop ----+
| +-------------+ (((-+ WiFi STA |
+- Router ----+ | | 192.168.1.5 |
| Firewall | | +- PC#2 ------+ +-------------+
(Internet)---WAN-+ DHCP server +-LAN-+---+ 192.168.1.3 |
| 192.168.1.1 | | +-------------+
+-------------+ |
| +- PC#1 ------+
+---+ 192.168.1.4 |
+-------------+
This can be done using the inbuilt wireless features of the Raspberry Pi 4, Raspberry Pi 3 or Raspberry Pi Zero W, or by using a suitable USB wireless dongle that supports access point mode. It is possible that some USB dongles may need slight changes to their settings. If you are having trouble with a USB wireless dongle, please check the forums.
This documentation was tested on a Raspberry Pi 3B running a factory installation of Raspbian Buster Lite (Jul. 2019).
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Ensure you have administrative access to your Raspberry Pi. The network setup will be entirely reset as part of the installation: local access, with screen and keyboard connected to your Raspberry Pi, is recommended.
Note: If installing remotely through SSH,
- Connect to your Raspberry Pi by name, e.g.
ssh pi@raspberrypi.local. The IP address of your Raspberry Pi on the network will probably change after installation. - Be ready to add screen and keyboard in case you lose contact with your Raspberry Pi after installation.
- Connect to your Raspberry Pi by name, e.g.
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Connect your Raspberry Pi to the ethernet network and boot the Raspbian OS.
-
Ensure the Raspbian OS on your Raspberry Pi is up to date and reboot if packages were installed in the process.
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Have a wireless client (laptop, smartphone, ...) ready to test your new access point.
In order to work as a bridged access point, the Raspberry Pi needs to have the hostapd access point software package installed:
sudo apt install hostapd
Enable the wireless access point service to start when your Raspberry Pi boots:
sudo systemctl unmask hostapd
sudo systemctl enable hostapd
Software installation is complete. We will configure the access point software later on.
A bridge network device in the Raspberry Pi will join the ethernet and wireless networks using its built-in interfaces.
Add a bridge network device named br0 by creating the following file:
sudo nano /etc/systemd/network/bridge-br0.netdev
[NetDev]
Name=br0
Kind=bridge
In order to bridge the ethernet network with the wireless network, first add the built-in ethernet interface (eth0) as bridge member with the following file:
sudo nano /etc/systemd/network/br0-member-eth0.network
[Match]
Name=eth0
[Network]
Bridge=br0
Note: The access point software will add the wireless interface wlan0 to the bridge when the service starts. There is no need to create a file for that interface. This situation is particular to WiFi network interfaces.
Now enable the systemd-networkd service to create and populate the bridge when your Raspberry Pi boots:
sudo systemctl enable systemd-networkd
Network interfaces that are members of a bridge device are never assigned an IP address, since they communicate via the bridge. The bridge device itself needs an IP address, so that you can reach your Raspberry Pi on the network.
dhcpcd, the DHCP client on the Raspberry Pi, automatically requests an IP address for every active interface. So we need to block the eth0 and wlan0 interfaces from being processed, and let dhcpcd only configure br0 via DHCP.
sudo nano /etc/dhcpcd.conf
Add the following line near the beginning of the file (above the first interface xxx line, if any):
denyinterfaces wlan0 eth0
Interface br0 will be configured as per defaults via DHCP, no specific entry is necessary. Save the file to complete the IP configuration of the machine.
Create the hostapd configuration file, located at /etc/hostapd/hostapd.conf, to add the various parameters for your wireless network.
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)
interface=wlan0
bridge=br0
ssid=NameOfNetwork
hw_mode=g
channel=7
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
Note the lines interface=wlan0 and bridge=br0: these direct hostapd to add the wlan0 interface as bridge member to br0 when the access point starts, completing the bridge between ethernet and wireless.
It is now time restart your Raspberry Pi and verify the wireless access point becomes automatically available.
sudo systemctl reboot
Once your Raspberry Pi has restarted, search for WiFi networks with your wireless client. The network SSID you specified in file /etc/hostapd/hostapd.conf should now be present, and it should be accessible with the specified password.
Your wireless client should have access to the local network and the Internet.