Raspberry Pi

The scope of this article is the installation steps taken to produce a local area network using a RaspberryPi 3, running Raspbian Jessy Lite, with a bridged internet connection via an Ethernet cable to facilitate both the Hackers & Designers workshops around basic Unix and program skills for designers, and the Frankenstein Bot workshop by Constant.

Code blocks that begin with "$" denote terminal, command line instructions, all other code blocks denote configuration files and/or program source code.

In all locations where "vi" is used, feel free to use another text editor of your choice (ex. nano).

Setting up the network

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These instructions are taken largely from here, but are reiterated in the case article disappears from the internet.

We need to tell dhcpcd to ignore the wlan0 interface.

$ sudo vi /etc/dhcpcd.conf

Add the following line to the bottom of the file:

denyinterfaces wlan0

wlan0 will need a static ip address.

$ sudo vi /etc/network/interfaces

The file should contain, everything else can be commented out or deleted:

   auto lo
   iface lo inet loopback
   allow-hotplug eth0
   iface eth0 inet dhcp
   allow-hotplug wlan0
   iface wlan0 inet static
       address 10.1.1.1
       netmask 255.255.255.0
       network 10.1.1.0
       broadcast 10.1.1.255

Install hostapd, and configure it.

$ sudo apt-get install hostapd

$ sudo vi /etc/hostapd/hostapd.conf

   interface=wlan0
   driver=nl80211
   ssid=Hackers & Designers
   hw_mode=g
   channel=6
   ieee80211n=1
   wmm_enabled=1
   ht_capab=[HT40][SHORT-GI-20][DSSS_CCK-40]
   macaddr_acl=0
   ignore_broadcast_ssid=0

$ sudo vi /etc/default/hostapd

Uncomment and set the following value:

DAEMON_CONF="/etc/hostapd/hostapd.conf

Install and configure dnsmasq.

$ sudo apt-get install dnsmasq

   interface=wlan0
   listen-address=10.1.1.1
   bind-interfaces
   server=8.8.8.8
   domain-needed
   bogus-priv
   dhcp-range=10.1.1.50,10.1.1.250,12h

For the purposes of the Frankenstein "hovel" bot, also uncomment:

   log-queries
   log-dhcp

Setup IPv4 forwarding.

$ sudo vi /etc/sysctl.conf

Uncomment the following line.

net.ipv4.ip_forward=1

Execute the following.

   $ 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
   $ sudo sh -c "iptables-save > /etc/iptables.ipv4.nat"

To ensure the forwarding persists beyond restarts.

$ sudo vi /etc/rc.local

Add the following line before exit(0).

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

Restart and verify the network is working.

$ sudo reboot