Change Ubuntu Server from DHCP to a Static IP Address

Ever need to quickly assign a static IP to your new Ubuntu server installation? Here's an article that explains how to do it.

If the Ubuntu Server installer has set your server to use DHCP, you will want to change it to a static IP address so that people can actually use it.

Changing this setting without a GUI will require some text editing, but that’s classic linux, right?

Let’s open up the /etc/network/interfaces file. I’m going to use vi, but you can choose a different editor

sudo vi /etc/network/interfaces

For the primary interface, which is usually eth0, you will see these lines:

auto eth0
iface eth0 inet dhcp

As you can see, it’s using DHCP right now. We are going to change dhcp to static, and then there are a number of options that should be added below it. Obviously you’d customize this to your network.

auto eth0
iface eth0 inet static
        address 192.168.1.100
        netmask 255.255.255.0
        network 192.168.1.0
        broadcast 192.168.1.255
        gateway 192.168.1.1

Now we’ll need to add in the DNS settings by editing the resolv.conf file:

sudo vi /etc/resolv.conf

On the line ‘name server xxx.xxx.xxx.xxx’ replace the x with the IP of your name server. (You can do ifconfig /all to find out what they are)

You need to also remove the dhcp client for this to stick (thanks to Peter for noticing). You might need to remove dhcp-client3 instead.

sudo apt-get remove dhcp-client

Now we’ll just need to restart the networking components:

sudo /etc/init.d/networking restart

Ping www.google.com. If you get a response, name resolution is working(unless of course if google is in your hosts file).

Really pretty simple.

Source: http://www.howtogeek.com/howto/ubuntu/change-ubuntu-server-from-dhcp-to-a-static-ip-address/