Raspberry pi as Wi-Fi repeater

This is a simple guide to set Raspberry pi as Wi-Fi repeater, I know there are many guides out there, including the official, but none of them worked 100% without modifications.

Based on: Linux raspberrypi 5.10.17-v7+ (Raspbian 10 buster)

In order to achieve our goal we will need to set up two separate interfaces, You will need additional Wi-Fi usb device or use the ethernet connection.

Let's assume your home lan address is 10.0.0.0/24, We will extend this network using another lan at address 10.0.1.0/24.

This guide assumes the OS is a clean installation and running, with the Wi-Fi\ethernet interface to the router "10.0.0.0/24" is set up.

                                               this interface is being configured
                                                    (10.0.1.0/24 network)
# Option 1                                                    |
                                                              |
                 +- Router ----+          +--- Raspberry ---+ /        +- Laptop ----+
                 | DHCP server |          | 10.0.0.18       |/         | WLAN Client |
(Internet)---WAN-+             +---LAN----|/        WLAN AP +-)))  (((-+             |
                 | 10.0.0.0/24 |          |        10.0.1.1 |          | 10.0.1.36   |
                 +-------------+          +-----------------+          +-------------+


# Option 2
                 +- Router ----+          +--- Raspberry ---+          +- Laptop ----+
                 | DHCP server |   WiFi   | 10.0.0.18       |          | WLAN Client |
(Internet)---WAN-+             +-)))  (((-|/        WLAN AP +-)))  (((-+             |
                 | 10.0.0.0/24 |          |        10.0.1.1 |          | 10.0.1.36   |
                 +-------------+          +-----------------+          +-------------+

Automatic Installation via Ansible:

Execute from project root directory
(note for the , below, or the ip/dns will be considered a hosts inventory filename) the configured device ip from above example is 10.0.0.18

if updating country variable make sure country is a valid Alpha-2 code ISO 3166-1 country code

Custom access point CIDR can be provided by passing these variables: (view defaults)

ap_ip_addr="10.0.1.1/24"
ap_start_ip_addr="10.0.1.2"
ap_end_ip_addr="10.0.1.100"
ap_subnet_mask="255.255.255.0"

option 1 install example:

With option one you bridge eth0 <-> wlan0 and probably connected to raspberry pi via LAN Ethernet cable (to ip 10.0.0.18), so only the configured access point name/pass should be provided (if not provided default ap_ssid_name and ap_ssid_pass will be set to nalkinscloud)

ansible-playbook -u pi --ask-pass \
    -i "10.0.0.18," \
    ansible/setup_repeater.yaml \
    -e ap_ssid_name=AP_SSID \
    -e ap_ssid_pass=AP_PASSWORD \
    -e country="FI"

option 2 install example:

With option two you bridge wlan0 <-> wlan1 and probably want to ssh to raspberry via the Wi-Fi interface (10.0.0.8), in this case you should manually set up wpa_supplicant as described below.
If you connected via ethernet cable (to lets say 10.0.0.37) update relevant ip host.
the ssid_name and ssid_pass should contain your home Wi-Fi access.

ansible-playbook -u pi --ask-pass \
    -i "10.0.0.18," \
    ansible/setup_repeater.yaml \
    -e ap_ssid_name="AP_SSID>" \
    -e ap_ssid_pass="<AP_PASSWORD>" \
    -e ssid_name="<LAN_SSID>" \
    -e ssid_pass="<LAN_PASSWORD>"

default password for pi user is: raspberry

Manual Installation:

When doing ip a you should have 4\3 interfaces, loopback, eth0 for lan cable connection, wlan0 is the onboard Wi-Fi and wlan1 is the usb Wi-Fi interface if connected.

wlan1 or eth0 will connect to your home LAN at 10.0.0.0/24
wlan0 will create a new network using 10.0.1.0/24 then a bridge (br0) will bridge the interfaces.

for option 2 only set up (not needed when using eth0 connection to router), provide your home SSID and password sudo vi /etc/wpa_supplicant/wpa_supplicant.conf

# update with relevant country
country=US
network={
    ssid="YOUR_HOME_SSID"
    psk="WIFI_PASSWORD"
}

Once raspberry was able to connect to the router (with internet access), do

sudo apt-get update
sudo apt-get upgrade
sudo apt-get install dnsmasq hostapd bridge-utils

Now configure a static IP for wlan1 (or eth0) and static IP for wlan0 sudo vi /etc/dhcpcd.conf Add to the end of file lines:

## If using static IP with additional wifi (optional)
#interface wlan1
#    static ip_address=10.0.0.2/24
#    static routers=10.0.0.1
#    static domain_name_servers=10.0.0.1 8.8.8.8

## If using static IP with ethernet (optional)
#interface eth0
#    static ip_address=10.0.0.2/24
#    static routers=10.0.0.1
#    static domain_name_servers=10.0.0.1 8.8.8.8

interface wlan0
    static ip_address=10.0.1.1/24
    nohook wpa_supplicant

Restart the service sudo service dhcpcd restart

Set up the DHCP server (dnsmasq)

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

And append

interface=wlan0
    dhcp-range=10.0.1.2,10.0.1.100,255.255.255.0,12h

Configure Access Point (hostapd)

type sudo vi /etc/hostapd/hostapd.conf And append

# update with relevant country
country_code=US
interface=wlan0
driver=nl80211

ssid=[AP_SSID]
hw_mode=g
channel=6
wmm_enabled=0
macaddr_acl=0
auth_algs=1
ignore_broadcast_ssid=0
wpa=2
wpa_passphrase=[AP_PASS]
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP

Execute sudo vi /etc/default/hostapd and replace line #DAEMON_CONF with DAEMON_CONF="/etc/hostapd/hostapd.conf"

Ensure wireless operation (comply regulations)

sudo rfkill unblock wlan

Start the services

sudo systemctl start hostapd
sudo systemctl start dnsmasq

Add Routing

type sudo vi /etc/sysctl.conf and uncommon line:

net.ipv4.ip_forward=1

Then run

## if using eth0 as connection to router
#inter=eth0
inter=wlan1

sudo iptables -t nat -A POSTROUTING -o ${inter} -j MASQUERADE
sudo sh -c "iptables-save > /etc/iptables.ipv4.nat"

Edit sudo vi /etc/rc.local and append above "exit 0" line

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

only if setting wlan1 append to /etc/network/interfaces file:

# Bridge setup
auto br0
iface br0 inet manual
bridge_ports wlan1 wlan0

Then sudo reboot

bmoffatt/Raspberry-WiFi-Repeater