Configuring a Static IP address on your Raspberry Pi
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Basic Setup - for help with buying / selecting other hardware and setting it up.
Beginners Guide - you are up and running, now what can you do?
Latest RPi 4 Topics - Recent topics on Raspberry Pi 4 and the Pi OS
Advanced Setup - for more extensive information on setting up.
Trouble Shooting - some things to check if things don't work as expected.
Configure eth0 to not use DHCP
By default the Raspberry Pi uses DHCP to configure its network interfaces, including, on the model B, the built-in ethernet port. If you want to change this so the ethernet port has a static IP address, here's how.
DHCP for eth0 is enabled in the file /etc/network/interfaces. Here is what it looks like by default on a Raspberry Pi under the official version of Raspbian:
auto lo iface lo inet loopback iface eth0 inet dhcp allow-hotplug wlan0 iface wlan0 inet manual wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf iface default inet dhcp
(Note: there is no actual wlan0 interface unless you attach a wireless USB network adapter. The entries that refer to wlan0 are there for when you do ;-) ).
Instead of the line:
iface eth0 inet dhcp
you need lines like this:
iface eth0 inet static address 192.168.1.1 netmask 255.255.255.0 gateway 192.168.1.254
The above example assigns the address 192.168.1.1 to eth0 with a subnet mask of 255.255.255.0, and sets the default gateway to 192.168.1.254.
Edit the file /etc/network/interfaces with the nano utility like this:
sudo nano /etc/network/interfaces
The second thing you need to do is check that you have a valid DNS server listed in /etc/resolv.conf. Edit this file using nano and add your DNS server if it is not already there. If you are using a broadband router, add the address of your router as the DNS server.