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. 


sudo iptables -L

Chain INPUT (policy ACCEPT)
target    prot opt source      destination

Chain FORWARD (policy ACCEPT)
target    prot opt source      destination

Chain OUTPUT (policy ACCEPT)
target    prot opt source      destination

/etc/resolv.conf says:
nameserver 192.168.0.1