Easy Understanding - Setting the Static Network Configuration

It is not intuitively obvious how to assign Ubuntu 10.04 Lucid Lynx a a static IP address from the command line. However, much of Linux administration involves the editing of text files, and assigning a static IP address is no different. You’ll need to edit the following file:

[root@localhost~:]#/etc/network/interfaces

Initially, the file only contains information about your local loopback address:

auto lo
iface lo inet loopback

To assign a static IP address, you’ll need to make some changes to this file.

Let’s say you want to assign a static IP of 192.168.1.2 to your eth0 network connection (the first Ethernet adapter on your system; if you only have one, it will be eth0), with a subnet mask of 255.255.255.0 and a local gateway of 192.168.1.1. First, make a backup copy of the interfaces file:

[root@localhost~:]#cp /etc/network/interfaces /etc/network/interfaces.bkp

This will make a backup copy in your home directory in case something goes amiss during the editing process. Next, fire up a text editor:

[root@localhost~:]#nano /etc/network/interfaces

Once the file is open, add the following lines:

iface eth0 inet static
address 192.168.1.2
netmask 255.255.252.0
gateway 192.168.1.1

Once you’ve added these lines, save the interfaces file to disk, and exit your text editor. If you want to add a static DNS server, you’ll need to edit the /etc/resolv.conf file with this command:

[root@localhost~:]#nano /etc/resolv.conf

To set a static DNS server with the address of 192.168.1.10, add this line to the file:

nameserver 192.168.1.10

Save the file, and exit your text editor.

You’ll then to need have your system load the new IP configuration. You can do that by rebooting, but if that takes too long, you can use this command to force Ubuntu to re-read the configuration files:
[root@localhost~:]#ifup eth0

Your system will then have a static IP address.