Network configuration in Debian

Automatic activation at startup

In order for certain interfaces to be activated automatically during the boot process, these must be entered with the auto parameter in the configuration file.The following example shows a system with a network card eth0 (the loopback interface lo should also always be activated):

auto lo eth0

Configuration of the individual interfaces

The following examples show different possible network interface configurations

Configuration of the loopback interface

The loopback interface should always be present and is also entered automatically:

iface lo inet loopback

Configuration of a static IP address

A static IP address is iface eth0 inet staticconfigured by means of .The following example shows the configuration with an IP address, a subnet mask, a default gateway and a DNS server:

iface eth0 inet static 
        address 192.168.0.111 
        netmask 255.255.255.0
        gateway 192.168.0.1
        dns-search somedomain.org
        dns-nameservers 192.168.0.1

Configuring a Dynamic IP Address (DHCP)

A dynamic IP address is iface eth0 inet dhcpconfigured by:

iface eth0 inet dhcp

Example of a system with two network cards

The following example shows the configuration file of a system with two network adapters. The first network card (eth0) automatically gets an IP address via DHCP (a default gateway is also configured here by DHCP). The second network card (eth1) is configured with a fixed IP address.

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

# The loopback network interface
car lo eth1
iface lo inet loopback

# The primary network interface
allow-hotplug eth0
iface eth0 inet dhcp

iface eth1 inet static
	address 192.168.56.2
	netmask 255.255.255.0
debian: ~ #