Linux as WiFi AP Bridge

For Linux / Raspberry Pi

Method 1: Use Network Manager

Ref: Configuration - Raspberry Pi Documentation

• Recommended

Bridge interface

Create the bridge interface

sudo nmcli connection add type bridge con-name 'Bridge' ifname br0

Add eth0 to the bridge

sudo nmcli connection add type ethernet slave-type bridge \
    con-name 'Ethernet' ifname eth0 master br0

Add a HotSpot to the bridge

sudo nmcli connection add con-name 'HotSpot' \
    ifname wlan0 type wifi slave-type bridge master br0 \
    wifi.mode ap wifi.ssid Hotspot wifi-sec.key-mgmt wpa-psk \
    wifi-sec.proto rsn wifi-sec.pairwise ccmp \
    wifi-sec.psk <WiFi password>

or

Use nmtui ▶ Edit a connection ▶ Bridge ▶ Edit... ▶ Add ▶ WiFi ▶

Profile name	HotSpot
Device	wlan0
SSID	Hot Spot
Mode	Access Point
Security	WPA & WPA2 Personal or WPA3 Personal
Password	<Password>

Activate the interface

Activate the bridge

sudo nmcli connection up Bridge

Active the HotSpot

sudo nmcli connection up HotSpot

Method 2: Use hostapd

• Unable to auto activate the bridge at boot

Install hostapd

sudo apt update
sudo apt install hostapd

Bridge interface

For systemd-networkd:

Ref: Network bridge - ArchWiki

Method 1

Use the nmtui (Text UI) to create

Method 2

Create a bridge br0

sudo nmcli connection add type bridge ifname br0

Add the interface eth0 to the bridge

sudo nmcli connection add type bridge-slave ifname eth0 master br0

Bring the bridge interface up

sudo nmcli connection up bridge-br0
sudo nmcli connection up bridge-slave-eth0

note

Bridge interface does NOT need sudo sysctl net.ipv4.ip_forward=1

Config hostapd

Ref: hostapd.conf

Create the config file /etc/hostapd/hostapd.conf

hw_mode	Description
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)

/etc/hostapd/hostapd.conf

interface=wlan0
bridge=br0
hw_mode=g
channel=7


# 0 = accept unless in deny list
# 1 = deny unless in accept list
# 2 = use external RADIUS server (accept/deny lists are searched first)

# macaddr_acl=0


# Empty SSID
# default: disabled (0)
# 1 = send empty (length=0) SSID in beacon and ignore probe request for
#     broadcast SSID
# 2 = clear SSID (ASCII 0), but keep the original length (this may be required
#     with some clients that do not support empty SSID) and ignore probe
#     requests for broadcast SSID

# ignore_broadcast_ssid=0


ssid=<WiFi SSID>

# 1=WPA, 2=WEP, 3=Both
auth_algs=1

# Bit 0 = WPA, Bit 1 = WPA2 and WPA3
wpa=2

wpa_passphrase=<WiFi password>
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP

Restart hostapd

sudo systemctl restart hostapd.service