/etc/network/interfaces Ubuntu Linux networking example

The /etc/network/interfaces file is used to configure network interfaces on Ubuntu Linux systems. The file contains a list of network interfaces and their configuration settings.

Here is an example of the /etc/network/interfaces file that configures a static IP address for the eth0 interface:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

source /etc/network/interfaces.d/*

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet static
        address 192.168.1.100
        netmask 255.255.255.0
        gateway 192.168.1.1
        dns-nameservers 8.8.8.8 8.8.4.4

In this example, the eth0 interface is configured with a static IP address of 192.168.1.100, a netmask of 255.255.255.0, and a default gateway of 192.168.1.1. The dns-nameservers option specifies the DNS servers to use for name resolution.

To configure the eth0 interface to use DHCP, you can set the iface option to dhcp and remove the address, netmask, and gateway options: