Using a Raspberry Pi 3 as a Wifi access point and bridge

Pi3_as_WiFi_AP_Bridge.md

The specificity of my setup, is that the Raspberry won’t be a router but a bridge. DHCP is thus delegated to the main ADSL router and all devices connected to the AP will appear on the same network than other devices. The instructions below are based on a fresh Raspbian lite install so that it can be reproduced easily.

Install the required packages :

$ sudo apt-get install -y bridge-utils hostapd

To create a bridge, we need to enable ip_forward in the kernel, for that, edit /etc/sysctl.conf and remove comment (#) from the following line :

net.ipv4.ip_forward=1

Then configure your network to create a bridge with eth0, in /etc/network/interfaces :

auto lo
iface lo inet loopback

# Disable eth0 / wlan0 config, handled by bridge
auto eth0
iface eth0 inet manual

allow-hotplug wlan0
iface wlan0 inet manual

# Create a bridge with static IP
auto br0
iface br0 inet dhcp
  bridge_ports eth0

You may have noticed that wlan0 is not configured in bridge br0. This is because hostapd will handle this once the access point is ready. So, next step is to configure the access point. For this, edit the file /etc/hostapd/hostapd.conf :

# First part is about configuring the access point and is copied from reference 1
interface=wlan0
driver=nl80211
hw_mode=g
channel=6
ieee80211n=1
wmm_enabled=1
ht_capab=[HT40][SHORT-GI-20][DSSS_CCK-40]
macaddr_acl=0
auth_algs=1
ignore_broadcast_ssid=0
wpa=2
wpa_key_mgmt=WPA-PSK
rsn_pairwise=CCMP
# This part is about setting SSID and WPA2 password
ssid=wifi_ssid
wpa_passphrase=wifi_password
# This line ask hostapd to add wlan0 to the bridge br0
bridge=br0

Now we need to tell hostapd to use our config. For that, edit /etc/default/hostapd and set:

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

Ok, here we go, just reboot the Pi and waaaw!

sudo reboot

Hello. Thank you for the approach above. This worked best for me, having looked at a couple of other solutions, including the routing options.

A couple of observations following your instructions above:

I had to unmask and enable hostapd for this to work:

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

I also needed to add in country_code=GB to the hostapd.conf file

I think because I'd not unmasked and enabled hostapd initially, I got a "soft block" on the wlan0 interface - that needed unblocking using :

rfkill unblock all

is it possible to make wlan1 the client and wlan0 the ap?

Good lord I've tried to get this to work for many hours and this one works immediately. Thanks a ton!

is there a way to route the RPi connected devices via VPN on top?

Thank you for the config. allow-hotplug wlan0 is really an important thing I've missed

Thanks for sharing this, I've also spent a while trying to get this to work on a pi 4 and this is the first thing that worked (used my own hostapd.conf though).

Right now I access my raspberry via ssh and using the fixed ip.

This what I have in /etc/dhcpd.conf
# Example static IP configuration: interface eth0 static ip_address=192.168.0.2/24 static routers=192.168.0.1 static domain_name_servers=192.168.0.1 1.1.1.1

If I follow your guide how do I keep the fixed address and access via SSH? Thanks

Thanks, it works for an old pi2 with an usb wifi key