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How to create a WiFi hotspot

I wanted to use a Raspberry Pi 3 Model B to create a WiFi hotspot.

Table of contents
  1. Getting started
    1. Prerequisites
  2. Installation
  3. dnsmasq.conf
  4. hostapd.conf
  5. hotspot.sh
  6. Authors
  7. Acknowledgments

Getting started

This is how I created a WiFi hotspot on my wlan0 interface with a DHCP server and DNS, that would send internet traffic out on interface eth0.

Prerequisites

  • Kali Linux 4.19.66-Re4son-v7+
  • Raspberry Pi 3 Model B

Installation

Install hostapd (hotspot server) and dnsmasq (dns and dhcp server):

root@kali:~# apt get install hostapd dnsmasq

Prevent the installed services starting at the boot:

root@kali:~# service hostapd stop
root@kali:~# service dnsmasq stop
root@kali:~# sudo update-rc.d hostapd disable
root@kali:~# sudo update-rc.d dnsmasq disable

dnsmasq.conf

Secure a copy of the original dnsmasq.conf file:

root@kali:~# mv /etc/dnsmasq.conf /etc/dnsmasq.conf.bak

Create dnsmasq.conf from scratch (take a look at the original dnsmasq.conf.bak file to see all options you have):

root@kali:~# nano /etc/dnsmasq.conf

# Never forward plain names (without a dot or domain part)
domain-needed
# Never forward addresses in the non-routed address spaces.
bogus-priv
# Bind
bind-dynamic
# Forward DNS to google
server=8.8.8.8
# Supply the range of addresses available for lease and 
# optionally a lease time (12 hrs)
dhcp-range=192.168.150.10,192.168.150.30,255.255.255.0,12h
# If you want dnsmasq to listen for DHCP and DNS requests only on
# specified interfaces (and the loopback) give the name of the
# interface (eg eth0) here.
# Repeat the line for more than one interface.
interface=wlan0

hostapd.conf

Create and setup the configuration file of hostapd:

root@kali:~# nano /etc/hostapd.conf

# Select the hotspot interface
interface=wlan0
# Name of WiFi
ssid=BerrySpot
# Set access point hardware mode to 802.11n (e.g. 2.4GHz)
hw_mode=g
# Meaning
ieee80211n=1
# Select WiFi channel
channel=6

hotspot.sh

Create hotspot.sh:

root@kali:~# nano hotspot-wlan0.sh

#!/bin/bash
#Start
sudo ifconfig wlan0 192.168.150.1
sudo service dnsmasq restart
sudo sysctl net.ipv4.ip_forward=1
sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
sudo hostapd /etc/hostapd.conf
#Stop
sudo iptables -D POSTROUTING -t nat -o eth0 -j MASQUERADE
sudo sysctl net.ipv4.ip_forward=0
sudo service dnsmasq stop
sudo service hostapd stop

Make hotspot.sh executable:

root@kali:~# chmod +x hotspot.sh

Execute the script hotspot.sh and go on your other WiFi device to see if it is up:

root@kali:~# ./hotspot-wlan0.sh

Authors

Mr. Johnson

Acknowledgments