Plug the USB WiFi adapter into one of the free USB ports on the Raspberry Pi. Power up the Raspberry Pi. At this point you need to either connect to the Raspberry Pi via an Ethernet cable or use a keyboard and a monitor to access the Raspberry Pi.
After booting and logging-in you want to make sure that the Raspberry Pi found your new wireless adapter. To look at which peripherals the operating system found when booting run the following command:
dmesg | more
You can use the spacebar to scroll down a page at a time – towards the end you will see something similar to the following lines:
[ 3.282651] usb 1-1.2: new high-speed USB device number 4 using dwc_otg
[ 3.394810] usb 1-1.2: New USB device found, idVendor=7392, idProduct=7811
[ 3.407489] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 3.420530] usb 1-1.2: Product: 802.11n WLAN Adapter
This means that the operating system recognized the USB WiFi Adapter using one of the built-in drivers (you can return to the terminal by pressing “q”). All that is left is to configure your WiFi connection.
Install the router software
In order for the Raspberry Pi to act as a WiFi router and access point you need to install some extra software on the Raspberry. You are going to need the following pieces of software:
- hostapdHostAPD is a user space daemon for access point and authentication servers. That means it can will turn your Raspberry Pi into a access point that other computers can connect to. It will also handle security such that you can setup a WiFi password.
- isc-dhcp-serverisc-dhcp-server is the Internet Systems Consortium’s implementation of a DHCP server. A DHCP server is responsible for assigning addresses to computers and devices connection to the WiFi access point.
To install the DHCP software run the following command:
sudo apt-get install isc-dhcp-server
Next up is the HostAPD software. Because our USB stick needs an access point driver not supported by the native HostAPD application we must install a custom version compiled with the driver we need. This can be done by running the following commands one at a time.
The whole crux of the issue is that the apt hosted copy of "hostapd" is not compatible with the RTL8188CUS chipset. But, thanks to the Edimax team, I've got a replacement "hostapd" binary to resolve this issue. This tutorial will not work without it.
To download and replace the installed binary version of "hostapd" we just installed, issue the following commands:
$ wget https://drive.google.com/open?id=0B9rimmaVzNREd0daY3dGYU5lMmM
// or $ wget https://github.com/jenssegers/RTL8188-hostapd/archive/v1.1.tar.gz
$ tar -xf hostapd_v1.1.tar.gz
$ make
$ make install
*Note, for those who don't like the idea of installing from untrusted 3rd parties, and would rather compiled their own binary, you can download the realtek driver
here. You will have to navigate to the
~/RTL8188C_8192C_USB_linux_v4.0.2_9000.20130911/wpa_supplicant_hostapd/wpa_supplicant_hostapd-0.8_rtw_r7475.20130812/hostapd and run a make, make install, then hostapd like what i did above.
Configure the ISC-DHCP-Server
To configure the DHCP server open the file /etc/dhcp/dhcpd.conf in your favorite text editor. You can open it in nano using this command:
sudo nano /etc/dhcp/dhcpd.conf
Find the following section and comment it out by placing a hashtag at the beginning of the line.
option domain-name "example.org";
option domain-name-servers ns1.example.org, ns2.example.org;
Next find the section below and un-comment the word authoritative (remove hastag):
# If this DHCP server is the official DHCP server for the local
# network, the authoritative directive should be uncommented.
#authoritative;
The file now looks like this:
Next we need to define the network and network addresses that the DHCP server will be serving. This is done by adding the following block of configuration to the end of file:
subnet 192.168.10.0 netmask 255.255.255.0 {
range 192.168.10.10 192.168.10.20;
option broadcast-address 192.168.10.255;
option routers 192.168.10.1;
default-lease-time 600;
max-lease-time 7200;
option domain-name "local-network";
option domain-name-servers 8.8.8.8, 8.8.4.4;
}
This will enable the DHCP server to hand out the ip addresses from 192.168.10.10 to 192.168.10.20 in its own local network. People who are skilled in network configuration can change these values if they wish to use some other network addresses and/or other DNS servers. This configuration will use the Google DNS servers at 8.8.8.8 and 8.8.4.4.
To save the file press Ctrl+O this will write the file to the disk – afterwards you can exit nano by pressing Ctrl+X. If nano asks if you want to Save modified buffer? press “Y” followed by hitting enter to confirm the filename.
Next file to edit is /etc/default/isc-dhcp-server, you can open it in nano using this command:
sudo nano /etc/default/isc-dhcp-server
Scroll down to the line saying interfaces and update the line to say:
INTERFACES="wlan0"
This will make the DHCP server hand out network addresses on the wireless interface. Save the file and exit nano.
The last step in configuring the DHCP server is to configure a static ip address for the wireless network adapter. This is done in the file /etc/network/interfaces – before opening it make sure the WLAN interface is down. Do this with the following commands:
sudo ifdown wlan0
sudo nano /etc/network/interfaces
Change the file to look like this:
This will make the wireless adapter take the address 192.168.10.1 in our new local network. Remember to comment out the last 3 lines of the file.
This concludes the setup of the DHCP server – however we still cannot connect to our new network because we have not setup the access point yet. This is done by configuring the hostapd application.
Configuring HostAPD
To configure HostAPD, open the file called /etc/hostapd/hostapd.conf in your favorite text editor. You can open it in nano using this command:
sudo nano /etc/hostapd/hostapd.conf
The standard configuration will create a new wireless network called wifi with the password YourPassPhrase. You can change the parameter “ssid=wifi” to the SSID wifi name you want and the parameter “wpa_passphrase=YourPassPhrase” to your own password.
This concludes the configuration of our access point software HostAPD. Next up is enabling NAT.
Enable NAT
The last step before we can start the access point is setting up Network Address Translation (NAT). This will make sure that our network traffic will be able to reach the internet using the Raspberry Pi’s Ethernet cable connection to your internet router.
Open /etc/sysctl.conf with:
sudo nano /etc/sysctl.conf
Scroll down to the last line of the file and add the line:
net.ipv4.ip_forward=1
Next start the translation right away by running:
sudo sh -c "echo 1 > /proc/sys/net/ipv4/ip_forward"
Start the wireless network by running:
sudo ifup wlan0
Next step is setting up the actual translation between the ethernet port called eth0 and the wireless card called wlan0.
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
With the NAT configured it is now time to run your access point for the first time.
Starting your wireless router
You are now ready to start the DHCP server and the HostAPD access point application.You can do so by running:
sudo service isc-dhcp-server start
sudo hostapd -dd /etc/hostapd/hostapd.conf
At this point you should be able to find your wireless network on your laptop and connect to it and the internet!
Finishing up …
While it is pretty cool you now have your Raspberry Pi running as a wireless access point it is not so cool you have to login every time it reboots to start the HostAPD and DHCP software…
To avoid this run the following commands:
sudo update-rc.d hostapd enable
sudo update-rc.d isc-dhcp-server enable
Adds "hostapd" to startup by editing
sudo nano /etc/default/hostapd
and uncomment the following line.
DAEMON_CONF="/etc/hostapd/hostapd.conf"
To avoid having to configure NAT every time the Raspberry Pi reboots you can do the following.
Run this command to backup the NAT configuration.
sudo sh -c "iptables-save > /etc/iptables.ipv4.nat"
Add the following to the end of the file /etc/network/interfaces to restore the configuration when the network interface comes up:
up iptables-restore < /etc/iptables.ipv4.nat
The file should now look like:
At this point try to reboot the raspberry pi just to make sure everything works as intended – you can reboot with the command:
sudo reboot
Hopefully you will see your new access point come online again. After it comes up again you should be able to connect to it and access the internet!
The standard configuration will create a new wireless network called wifi with the password YourPassPhrase. You can change the parameter “ssid=wifi” to the SSID wifi name you want and the parameter “wpa_passphrase=YourPassPhrase” to your own password.
