2022-11-24

Setting up a Raspberry Pi 3 as a access point and a router

1. Set Up WiFi Access Point

Install Packages

$ sudo apt-get install hostapd dnsmasq

hostapd turns wlan0 into an access point, and Dnsmasq plays an role of DHCP and DNS.

Set Static IP Address
First, set dhcp invalid in wlan0

$ sudo vi /etc/dhcpcd.conf

edit as follows:

~~dhcpcd.conf~~


denyinterfaces wlan0

Next, we need to set a static IP address for the WiFi interface.

$ sudo cp /etc/network/interfaces /etc/network/interfaces_org
$ sudo vi /etc/network/interfaces

At the bottom, add the following:

~~interfaces~~


allow-hotplug wlan0
iface wlan0 inet static
    address 172.20.5.1
    netmask 255.255.255.0
    network 172.20.5.0
    broadcast 172.20.5.255

Configure Hostapd

$ sudo vi /etc/hostapd/hostapd.conf

enter the folloing into that file:

~~hostapd.conf~~

interface=wlan0
driver=nl80211
hw_mode=g
channel=5
macaddr_acl=0
auth_algs=1
ignore_broadcast_ssid=0
ieee80211ac=0
wmm_enabled=1
ieee80211d=1
ieee80211h=1
country_code=JP
local_pwr_constraint=3
spectrum_mgmt_required=1
wpa=3
wpa_key_mgmt=WPA-PSK
ssid=raspberrypi
wpa_passphrase=**********

You can set ssid, passphrase, and it is better to select a channel which is not interfered by other interfaces.
Test your configuration file works good.

$ sudo hostapd /etc/hostapd/hostapd.conf

If it runs successfully, you can check ssid by other machine.

Then, we make this configuration enable by telling its place to hostapd.

$ sudo vi /etc/default/hostapd

Uncomment # and replace the line #DAEMON_CONF=""with:
DAEMON_CONF="/etc/hostapd/hostapd.conf"

Set hostapd runs automatically

$ sudo systemctl unmask hostapd.service
$ sudo systemctl enable hostapd.service

Configure Dnsmasq

Edit Dnsmasq configuration

$ sudo cp /etc/dnsmasq.conf /etc/dnsmasq.conf_org
$ sudo vi /etc/dnsmasq.conf

paste in the text below

~~dnsmasq.conf~~


interface=wlan0
listen-address=172.20.5.1
bind-interfaces
server=8.8.8.8
domain-needed
bogus-priv
dhcp-range=172.20.5.100,172.20.5.200,24h

Then restart the Raspberry Pi

$ sudo reboot

Now you can use Raspberry Pi as a Access Point.

2. Enable Packet Forwarding

-Configure NAT(Network Address Translation)

Edit /etc/sysctl.conf: uncomment net.ipv4.ip_forward=1 by deleting #.

$ sudo vi /etc/sysctl.conf

~~sysctl.conf~~

net.ipv4.ip_forward=1

Next, configure NAT(Network Address Translation).

$ sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
$ sudo iptables -A FORWARD -i eth0 -o wlan0 -m state --state RELATED,ESTABLISHED -j ACCEPT
$ sudo iptables -A FORWARD -i wlan0 -o eth0 -j ACCEPT

After reboot, Raspberry Pi will revert back to its previous state. So it is needed to save and restore these settings.

$ sudo sh -c "iptables-save > /etc/iptables.ipv4.nat"

$ sudo vi /etc/rc.local

In rc.local script, just above the exit 0 add the following

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

That's all for configuration.
Restart Raspberry Pi to test the setting works.

$ sudo reboot

Reference

Setting up a Raspberry Pi 3 as an Access Point - SparkFun Learn

2022-11-23

Connecting PC(Ubuntu 18.10) to RaspberryPi3(Raspbian stretch) via ethernet cable , setting static IP addresses

PC(Ubuntu18.10) と RaspberryPi3を有線LANでつなぐ

APIPA does not automatically assign IP adresses in Ubuntu, so I tried to set static IP adresses.

1. PC側

イーサネットデバイスを確認

$ ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp0s25: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc fq_codel state DOWN group default qlen 1000
    link/ether 68:f7:28:88:05:29 brd ff:ff:ff:ff:ff:ff

~~enp0s25に固定ipアドレスを付与する。~~

~~/etc/NetworkManager/system-connectionsディレクトリに構成ファイルを作成する。~~ ↑は既知のネットワークを記述しておく場所なのでこれではうまく行かない。

リンクローカル用yamlファイルを作成し、固定ipアドレスを設定する。

$ sudo vi /etc/netplan/01-netcfg-linklocal-staticIP.yaml

# Let NetworkManager manage all devices on this system
network:
  version: 2
  renderer: networkd

  ethernets:
    enp0s25:
      dhcp4: false
      addresses: [10.10.10.20/24]

2. Raspberry Pi側

$ ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether b8:27:eb:c2:cb:cf brd ff:ff:ff:ff:ff:ff
3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether b8:27:eb:97:9e:9a brd ff:ff:ff:ff:ff:ff
    inet 192.168.3.11/24 brd 192.168.3.255 scope global wlan0
       valid_lft forever preferred_lft forever
    inet6 2400:2410:ae60:fe00:7a68:da9a:9599:83bd/64 scope global mngtmpaddr noprefixroute dynamic 
       valid_lft 86062sec preferred_lft 14062sec
    inet6 fe80::1953:30df:7d21:9686/64 scope link 
       valid_lft forever preferred_lft forever

eh0に固有ipアドレスを設定する。 /etc/dhcpcd.confに以下のように記述

$ sudo vi /etc/dhcpcd.conf

interface eth0
static ip_address=10.10.10.10/24
static routers=
static domain_name_servers=
static domain_search=

設定を読み込ませて反映されるか確認

$ sudo /etc/init.d/dhcpcd restart

以上で両方の固有ipアドレスが設定された。

3. 通信の確認

pingを通してみる

$ ping 10.10.10.10
PING 10.10.10.10 (10.10.10.10) 56(84) bytes of data.
64 bytes from 169.254.158.85: icmp_seq=1 ttl=64 time=0.437 ms
64 bytes from 169.254.158.85: icmp_seq=2 ttl=64 time=0.411 ms
64 bytes from 169.254.158.85: icmp_seq=3 ttl=64 time=0.481 ms
64 bytes from 169.254.158.85: icmp_seq=4 ttl=64 time=0.477 ms
64 bytes from 169.254.158.85: icmp_seq=5 ttl=64 time=0.398 ms
64 bytes from 169.254.158.85: icmp_seq=6 ttl=64 time=0.374 ms
^C
--- 10.10.10.10 ping statistics ---
6 packets transmitted, 6 received, 0% packet loss, time 118ms
rtt min/avg/max/mdev = 0.374/0.429/0.481/0.046 ms

機器間での通信がされていることがわかる。