IN CLASS HOST-Access Point SETUP

In this experiment, the aim is to make raspberry pi as an access point of Wifi.


Items Required:

• Raspberry Pi. 
• Ethernet cable.
• WiFi adapter.
• SD Card with Raspbian installed in it.
• Power supply for your Pi & a Micro USB cable.

This post is about the experience of Host access point setup in class:

• Connect Raspberry Pi to the router.
• Change the password into desired one from "raspberry" which is by default.

Now getting into the protocols and type out commands in the command-line interpreter of the Raspberry Pi:

• The first step is to install the required packages for setting up access point by 

"sudo apt-get install dnsmasq hostapd "

( 'hostapd' - This is the package that allows you to use the built in WiFi as an access point. 'dnsmasq' - This is a combined DHCP and DNS server that's very easy to configure).

• Since I have used Raspberry Pi-3 which has very latest version of the RaspianThe interface configuration is handled by dhcpcd. It shall ignore wlan0, as we will be configuring it with a static IP address elsewhere. we do this by opening dhcpcd configuration file with "Sudo nano /etc/dhcpcd.conf" and add the following line in the dhcpcd "denyinterfaces wlan0".

• Static IP needs to be configured, with “sudo nano /etc/network/interfaces” and edit the wlan0 section should look as follows:

allow-hotplug wlan0  

iface wlan0 inet static  

    address 172.24.1.1

    netmask 255.255.255.0

    network 172.24.1.0

    broadcast 172.24.1.255

#    wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

Now, restart dhcpcd with sudo service dhcpcd restart and then reload the configuration for wlan0 with sudo ifdown wlan0; sudo ifup wlan0.

• Next step is to configure hostapd by creating a new configuration file sudo nano /etc/hostapd/hostapd.conf with the following contents:

# This is the name of the WiFi interface we configured above

interface=wlan0

# Use the nl80211 driver with the brcmfmac driver

driver=nl80211

# This is the name of the network

ssid=Pi3-AP

# Use the 2.4GHz band

hw_mode=g

# Use channel 6

channel=6

# Enable 802.11n

ieee80211n=1

# Enable WMM

wmm_enabled=1

# Enable 40MHz channels with 20ns guard interval

ht_capab=[HT40][SHORT-GI-20][DSSS_CCK-40]

# Accept all MAC addresses

macaddr_acl=0

# Use WPA authentication

auth_algs=1

# Require clients to know the network name

ignore_broadcast_ssid=0

# Use WPA2

wpa=2

# Use a pre-shared key

wpa_key_mgmt=WPA-PSK

# The network passphrase

wpa_passphrase=raspberry

# Use AES, instead of TKIP

rsn_pairwise=CCMP

"sudo /usr/sbin/hostapd /etc/hostapd/hostapd.conf" can be used to verify if the hostapd is working.

Until this stage was the work done in the class and rest was done as a homework assignment. The post followed by this post will clearly explain how it is done.

Open up the default configuration file with sudo nano /etc/default/hostapd and find the 

line #DAEMON_CONF="" and replace it with DAEMON_CONF="/etc/hostapd/hostapd.conf"

•  To Configure DNSMASQ create a new file with

sudo mv /etc/dnsmasq.conf /etc/dnsmasq.conf.orig

sudo nano /etc/dnsmasq.conf

and paste the file with the contents as follows:

interface=wlan0      # Use interface wlan0  

listen-address=172.24.1.1 # Explicitly specify the address to listen on  

bind-interfaces      # Bind to the interface to make sure we aren't sending things elsewhere  

server=8.8.8.8       # Forward DNS requests to Google DNS  

domain-needed        # Don't forward short names  

bogus-priv           # Never forward addresses in the non-routed address spaces.  

dhcp-range=172.24.1.50,172.24.1.150,12h # Assign IP addresses between 172.24.1.50 and 172.24.1.150 with a 12 hour lease time.

• Now the next step is to Setup IPv4 forwarding

This step enables packet forwarding

open up the sysctl.conf file with sudo nano /etc/sysctl.conf, and remove the # from the beginning of the line containing net.ipv4.ip_forward=1. This will enable it on the next reboot, but because we are impatient, activate it immediately with: 

sudo sh -c "echo 1 > /proc/sys/net/ipv4/ip_forward"

need to share our Pi's internet connection to our devices connected over WiFi by the configuring a NAT between our wlan0 interface and our eth0 interface. We can do this using the following commands:

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  

we need these rules to be applied every time we reboot the Pi, so run  sudo sh -c "iptables-save > /etc/iptables.ipv4.nat" to save the rules to the file /etc/iptables.ipv4.nat. Now we need to run this after each reboot, so open the rc.local file with sudo nano /etc/rc.local and just above the line exit 0, add the following line:

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

Now we are done with setting up our wifi on Raspberry Pi. This can be hosted using the following commands:

sudo service hostapd start

sudo service dnsmasq start

To check if we have got everything configured correctly reboot with “sudo reboot”

References:

• https://frillip.com/using-your-raspberry-pi-3-as-a-wifi-access-point-with-hostapd/