Paul Ligocki

Wireless Access Point Raspberry Pi Zero W

Raspberry Pi Logo

Raspberry Pi Wirless Access Point

Features

  • Access Point Server: (ap0) : LAN
    • Accept WiFi Clients
    • Provied IP address via DHCP (Allows reserved IPs/MAC binding)
    • Provied Internet access via NAT
  • WiFi Client: (wlan0) : WAN
    • Able to connect to other Access Points via its WAN (wlan0)
    • Obtain IP address via DHCP client from External Access Point

Configuration

Access Point

Interface: ap0
SSID: Pi-0-WiFi-AP
WPA2: 20pa33w0rd20
Network: 10.0.66.0/24
IP Address: 10.0.66.1
ap0 MAC:

WiFi Client

Interface: wlan0

Setting it Up

Disable IPv6

Disable IPv6

ip a
1: lo: mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
2: wlan0: mtu 1500 qdisc pfifo_fast state UP group default qlen 1000

Add New 802.11 Interface

Note the 1st line must match the real MAC of wlan0 otherwise ap0 will not initialize.

sudo nano /etc/udev/rules.d/70-persistent-net.rules
SUBSYSTEM=="ieee80211", ACTION=="add|change", ATTR{macaddress}=="b8:27:eb:ff:ff:ff", KERNEL=="phy0", \ RUN+="/sbin/iw phy phy0 interface add ap0 type __ap", \ RUN+="/bin/ip link set ap0 address b8:27:eb:ff:ff:ff"
sudo reboot
ip a
1: lo: mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
2: wlan0: mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
3: ap0: mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000

Install Dnsmasq & Hostapd

DNSMasq will be used as a DHCP Server and HostAPD as a WiFi Access Point

sudo apt install dnsmasq hostapd -y
After this operation, 2,666 kB of additional disk space will be used.
Do you want to continue? [Y/n] y
sudo systemctl status dnsmasq
dnsmasq.service - dnsmasq - A lightweight DHCP and caching DNS server
Loaded: loaded (/lib/systemd/system/dnsmasq.service; enabled; vendor preset: enabled)
Active: active (running) since Sun 2099-13-33 00:01:53 BST; 1min 53s ago
Main PID: 677 (dnsmasq)
CGroup: /system.slice/dnsmasq.service
└─677 /usr/sbin/dnsmasq -x /run/dnsmasq/dnsmasq.pid -u dnsmasq -r /run/dnsmasq/resolv.conf -7 /etc/dnsmasq.d,.dpkg-dist,.dpkg-old,.dpkg-new --local-service --tru

Modify /etc/dnsmasq.conf

sudo nano /etc/dnsmasq.conf

interface=lo,ap0
no-dhcp-interface=lo,wlan0
bind-interfaces
server=8.8.8.8
domain-needed
bogus-priv
dhcp-range=192.168.99.50,192.168.99.150,12h
dhcp-host=ee:ee:ee:33:33:33,reservedhostname,192.168.99.151

Modify /etc/hostapd/hostapd.conf

Care is needed with hostapd.conf. Many problems were encountered while trying to set this up. Just to name a few issues ssid was too short, so was the password, a blank line at the end also. The errors that will get thrown are very generic and make troubleshooting difficult.

sudo nano /etc/hostapd/hostapd.conf

ctrl_interface=/var/run/hostapd
ctrl_interface_group=0
interface=ap0
driver=nl80211
ssid=PiAccessPoint
hw_mode=g
channel=11
wmm_enabled=0
macaddr_acl=0
auth_algs=1
wpa=2
wpa_passphrase=pipassword1
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP CCMP
rsn_pairwise=CCMP

Modify /etc/default/hostapd

sudo nano /etc/default/hostapd

DAEMON_CONF=”/etc/hostapd/hostapd.conf”

sudo systemctl status hostapd
hostapd.service
Loaded: masked (Reason: Unit hostapd.service is masked.)
Active: inactive (dead)
sudo systemctl unmask hostapd.service
sudo systemctl enable hostapd.service
Removed /etc/systemd/system/hostapd.service.
Synchronizing state of hostapd.service with SysV service script with /lib/systemd/systemd-sysv-install.
Executing: /lib/systemd/systemd-sysv-install enable hostapd

Populate Networks

WPA supplicat is used to define the networks that the WAN interface (wlan0) will connect to.

sudo nano /etc/wpa_supplicant/wpa_supplicant.conf

Or you can do this via

sudo raspi-config>Network Options>Wireless LAN

Modify /etc/network/interfaces

sudo nano /etc/network/interfaces

# interfaces(5) file used by ifup(8) and ifdown(8)

# Please note that this file is written to be used with dhcpcd
# For static IP, consult /etc/dhcpcd.conf and ‘man dhcpcd.conf’

#Include files from /etc/network/interfaces.d:
source-directory /etc/network/interfaces.d

auto lo
auto ap0
auto wlan0
iface lo inet loopback

allow-hotplug ap0
iface ap0 inet static
address 192.168.99.1
netmask 255.255.255.0
hostapd /etc/hostapd/hostapd.conf

allow-hotplug wlan0
iface wlan0 inet manual
wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf
iface AP1 inet dhcp
iface AP2 inet dhcp

Unreliable Results

Automated Workaround

touch fix-ap-wifi.sh
chmod +x fix-ap-wifi.sh
nano fix-ap-wifi.sh

#!/bin/bash
sleep 30
sudo ifdown –force wlan0 && sudo ifdown –force ap0 && sudo ifup ap0 && sudo ifup wlan0
sudo sysctl -w net.ipv4.ip_forward=1
sudo iptables -t nat -A POSTROUTING -s 192.168.99.0/24 ! -d 192.168.99.0/24 -j MASQUERADE
sudo systemctl restart dnsmasq

  • https://www.raspberrypi.org/products/raspberry-pi-zero/

paulligocki

,