Fifty Meters Range Wireless Access Point With TP Link WN7200ND USB Wireless Adapter on Raspbian Stretch

Raspberry Pi is great to create Secure Wireless Access Points but it
doesn’t have a good range, I used a TP Link WN7200ND USB Wireless Adapter to extend it. I want to share how to do it

Why do I want to use a raspberry pi instead of a router?

The answer is really simple, SECURITY. Router manufacturers just want to sell devices, they don’t care if there is a security flaw that will affect you. You raspberry pi will be up to date with the latest security patches.

Step 1: Install Raspbian Stretch Lite Image on a SD Card

Download Raspbian from Rapsberry Pi Download site and install it on a SD Card. If you want an easy to use Program to do it. I recommend Etcher.

Connect the TP Link WN7200ND Adapter to any of the USB ports, make sure that the power supply provides enough current. A power supply that provides 1 Ampere should be enough. The interface will be wlan1, internal R Pi Wifi adapter is wlan0.

Step 2: Edit DHCP Configuration

We don’t need a dynamic IP for the WN7200ND adapter so we need to change
the configuration file of dhcpd. Use a text editor edit the configuration file /etc/dhcpcd.conf and add the following line

denyinterfaces wlan1

Now we need to restart the DHCP service by using the command

sudo service dhcpcd restart

Step 3: Setup the Network Interfaces

Ethernet port eth0 will work normally (It will get a dynamic IP address when you connect it), but we need to setup a Bridge interface br0 that bridges the TP Link adapter wlan1 and Ethernet port eth0. Install bridge utils with the following command

sudo apt-get install bridge-utils

Setup the interfaces by creating a new text file /etc/network/interfaces.d/ap with the following text:

auto eth0
allow-hotplug eth0
iface eth0 inet manual 

auto wlan1
allow-hotplug wlan1
iface wlan1 inet manual
    pre-up service hostapd start
    post-up brctl addif br0 wlan1

auto br0
iface br0 inet dhcp
bridge_ports eth0 wlan1

Step 4: Install and Setup Hostapd

Hostapd implements the wireless access Point. Install it with the following command

sudo apt-get install hostapd

To setup the access point we need to setup hostapd. Create a new text file /etc/hostapd/hostapd.conf with the following text:

interface=wlan1 #wlan is WN7200ND adapter
driver=nl80211 # this is the driver required by WN7200ND

hw_mode=g # g means 2.4GHz band
channel=11 # this is the channel we will use, you can select any channel between 1 and 13 
ieee80211n=1 # limit frequencies to the ones allowed in your country
wmm_enabled=1 # 
ht_capab=[HT40][SHORT-GI-20] # setup the capabilities of WN7200ND

macaddr_acl=0 # comment this line to limit devices that can connect
#macaddr_acl=1 # uncomment this to limit devices that can connect

#accept_mac_file=/etc/hostapd/accept # this file has the list of mac addresses of the devices that hostapd will accept

ignore_broadcast_ssid=0 # will broadcast SSID

# Use WPA2
auth_algs=1
wpa=2   # USE WPA v2 only
wpa_key_mgmt=WPA-PSK
rsn_pairwise=CCMP

ssid=MyNetwork # use the name of your network
wpa_passphrase=MyUniquePassword # the passphrase for your network

To limit devices that will connect to the Access Point create the file /etc/hostapd/accept and enter the list of mac addresses like the following:

14:1a:93:eb:31:55 #mac address of your device

To load the configuration file when hostapd starts edit the file /etc/default/hostapd, uncomment DAEMON_CONF line and change it to

DAEMON_CONF="/etc/hostapd/hostapd.conf"

Step 5: Enable IP Forwarding

We need to enable IP forwarding for the bridge to work propery. To enable it edit edit the file /etc/sysctl.conf and uncomment the line net.ipv4.ip_forward=1

Step 6: Install and Setup DHCP Relay

To complete the setup and have all the devices on the same network (it
is a good idea to have everything on the same network if you want to use Chromecast or send videos to youtube on your smart TV). To send DHCP requests to ISP router we need to install isc dhcp relay and setup Pi to send requests to that server. To install it use the following command: