Raspberry PI 3 als AP
USING THE RASPBERRY PI 3 AS A WIFI ACCESS POINT WITH HOSTAPD
There's a new Raspberry Pi. This is exciting. It also has on-board WiFi. This makes it doubly exciting!
One of my first thoughts was, can I use it as a SoftAP for some ESP8266 sensor nodes? As it turns out, you can, and it's not that difficult, as the BCM43438chip is supported by the open-source brcmfmac driver!
The first step is to install the required packages: sudo apt-get install dnsmasq hostapd
I'll go into a little detail about the two:
· 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
If you want something a little more 'heavyweight', you can use the isc-dhcp-server and bind9 packages for DHCP and DNS respectively, but for our purposes, dnsmasq works just fine.
CONFIGURE YOUR INTERFACES
The first thing you'll need to do is to configure your wlan0 interface with a static IP.
If you're connected to the Pi via WiFi, connect via ethernet/serial/keyboard first.
In newer Raspian versions, interface configuration is handled by dhcpcd by default. We need to tell it to ignore wlan0, as we will be configuring it with a static IP address elsewhere. So open up the dhcpcd configuration file with sudo nano /etc/dhcpcd.conf and add the following line to the bottom of the file:
Note: This must be ABOVE any interface lines you may have added!
Now we need to configure our static IP. To do this open up the interface configuration file with sudo nano /etc/network/interfaces and edit the wlan0section so that it looks like this:
Restart dhcpcd with sudo service dhcpcd restart and then reload the configuration for wlan0 with sudo ifdown wlan0; sudo ifup wlan0.
Next, we need to configure hostapd. Create a new configuration file with sudo nano /etc/hostapd/hostapd.conf with the following contents:
We can check if it's working at this stage by running sudo /usr/sbin/hostapd /etc/hostapd/hostapd.conf. If it's all gone well thus far, you should be able to see to the network Pi3-AP! If you try connecting to it, you will see some output from the Pi, but you won't receive and IP address until we set up dnsmasq in the next step. Use Ctrl+C to stop it.
We aren't quite done yet, because we also need to tell hostapd where to look for the config file when it starts up on boot. 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".
The shipped dnsmasq config file contains a wealth of information on how to use it, but the majority of it is largely redundant for our purposes. I'd advise moving it (rather than deleting it), and creating a new one with
Paste the following into the new file:
SET UP IPV4 FORWARDING
One of the last things that we need to do before we send traffic anywhere is to enable packet forwarding.
To do this,
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"
We also 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 eth0interface. We can do this using the following commands:
However, 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:
WE'RE ALMOST THERE!
Now we just need to start our services:
And that's it! You should now be able to connect to the internet through your Pi, via the on-board WiFi!
To double check we have got everything configured correctly, reboot with sudo reboot.