Operation Manual

Chapter 4: Network Configuration
For most users, configuring the Pi’s network is as easy as plugging a cable into the Model B’s Ethernet port—or a USB
Ethernet adapter in the case of the Model A. For others, however, the network requires manual configuration.
If you know that your network doesn’t have a Dynamic Host Configuration Protocol (DHCP) server—a system that tells the Pi
and other devices on the network how they should connect—or if you want to use a USB wireless adapter with the Pi, read on.
Wired Networking
If the network still doesn’t work, you may need to configure it manually. Normally, the network in a home, school or office has a
DHCP server that tells the Pi and other devices on the network how they should connect. Some networks, however, don’t have
a DHCP server and need to be set up manually.
The list of network interfaces, along with information about how they should be configured, is stored in a file called interfaces
located in the folder /etc/network. This is a file only the root user can edit, because removing a network interface from this list
will cause it to stop working.
From the terminal, you can edit this file using a variety of different text editors. For simplicity, the nano text editor should be used
for this process. Open the file for editing with the following command:
sudo nano /etc/network/interfaces
Nano is a powerful yet lightweight text editor, with a simple user interface (see Figure 4-1). You can move your cursor around
the document with the arrow keys, save by holding down the CTRL key and pressing O, and quit by holding down the CTRL
key and pressing X.
The line you need to edit for manual configuration starts with iface eth0 inet. Delete dhcp from the end of this line and
replace it with static, press Enter to start a new line, and then fill in the remaining details in the following format with a tab at
the start of each line:
[Tab] address xxx.xxx.xxx.xxx
[Tab] netmask xxx.xxx.xxx.xxx
[Tab] gateway xxx.xxx.xxx.xxx
Make sure that you press the Tab key at the start of each line, and don’t actually type [Tab]. The x characters in the
configuration lines represent network addresses you’ll need to enter. For address, you should enter the static IP address that
you want to assign to the Pi. For netmask, you should enter the network mask—which controls the size of the connected
network—in what is known as dotted-quad format. If you’re using a home network, this is typically 255.255.255.0. For
gateway, you should enter the IP address of your router or cable modem.
As an example, the settings for a common home network would look like this:
iface eth0 inet static
[Tab] address 192.168.0.10
[Tab] netmask 255.255.255.0
[Tab] gateway 192.168.0.254
Figure 4-1: Editing /etc/network/interfaces with nano