Introduction

This tutorial for setting up Ubuntu Server (RPi 3B) as Wifi access point

Overview:

The main steps can be listed as following:

Install required packages
Setup hostapd
Setup DNSmasq
Configure AP IP Address

Install required packages

sudo apt-get install hostapd dnsmasq

Hostapd

The purpose of Hostapd is to set WiFi as an access point

we need to write a new config file for hostapd sudo vi /etc/hostapd/hostapd.conf

interface=wlan0
driver=nl80211
ssid=MyWiFiNetwork
hw_mode=g
channel=7
wmm_enabled=0
macaddr_acl=0
auth_algs=1
ignore_broadcast_ssid=0
wpa=2
wpa_passphrase=12345678
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP

Then we need to tell hostapd to use our config file, edit /etc/default/hostapd and change the line starts with #DAEMON_CONF, remember to remove #
```
DAEMON_CONF="/etc/hostapd/hostapd.conf"
```

Then Let's start hostapd

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

dnsmasq

The purpose of dnsmasq is to act as DHCP Server, so when a devies connects to Raspberry Pi it can get an IP assigned to it.
make a backup of default config by: sudo cp /etc/dnsmasq.conf /etc/dnsmasq.conf.org
Create a new config file by: sudo vi /etc/dnsmasq.conf
This config file will automatically assign addresses between 192.168.4.2 and 192.168.4.20 with lease time 24 hours.
```
interface=wlan0
dhcp-range=192.168.4.2,192.168.4.20,255.255.255.0,24h
```
Then Let's reload dnsmasq config
```
sudo systemctl reload dnsmasq
```

Solving startup Error:

On System startup, dnsmasq will not wait for wlan0 interface to initialize and will fail with error wlan0 not found.
We need to tell systemd to launch it after network get ready, so we will modify dnsmasq service file by adding After= and Wants= under [Unit] section.

sudo vi /lib/systemd/system/dnsmasq.service
```
[Unit]
...
After=network-online.target
Wants=network-online.target
```

Config static IP

Ubuntu uses cloud-init for initial setup, so will modify the following file to set wlan0 IP.
DON'T USE TABS IN THIS FILE, IT WILL NOT WORK, EVER!!
Modify the cloud-init file by sudo vi /etc/netplan/50-cloud-init.yaml

Add the following content to the file:

        wlan0:
            dhcp4: false
            addresses:
            - 192.168.4.1/24

The file will finally looks like this:

# This file is generated from information provided by
# the datasource.  Changes to it will not persist across an instance.
# To disable cloud-init's network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
    version: 2
    ethernets:
        eth0:
            dhcp4: true
            match:
                macaddress: 12:34:56:78:ab:cd
            set-name: eth0
        wlan0:
            dhcp4: false
            addresses:
            - 192.168.4.1/24

Finally:

Reboot your Raspberry Pi and check if you can connect to it over WiFi and can SSH.

Notes:

if you can't see Raspberry Pi Hot spot then hostapd is not working, you can check its logs by sudo systemctl status hostapd.
if you can coonect to Raspberry Pi but can't get an IP then dnsmasq is not working, you can check its logs by sudo systemctl status dnsmasq.

ExtremeGTX/Ubuntu_AP.md