Question

Change DNS server with bash

Hello,

To change DNS server you must change the values in /etc/network/interfaces. But the server I’m setting up is being up up by a Bash script, I need to be able to change the DNS server thru Bash.

Anyone having an idea how that can be done?


Submit an answer

This textbox defaults to using Markdown to format your answer.

You can type !ref in this text area to quickly search our full set of tutorials, documentation & marketplace offerings and insert the link!

Sign In or Sign Up to Answer

These answers are provided by our Community. If you find them useful, show some love by clicking the heart. If you run into issues leave a comment, or add your own answer to help others.

Accepted Answer

Hello @Geekologist,

By default on DigitalOcean Ubuntu 16.04 /etc/network/interfaces is populated with Google Public DNS - 8.8.8.8 - 8.8.4.4. If you open etc/network/interfaces with any text editor you will see following:

# 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
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet static
        address 111.111.111.111
        netmask 255.255.255.0
        gateway 111.111.111.0
        up ip addr add 10.17.0.6/16 dev eth0
        dns-nameservers 8.8.8.8 8.8.4.4

Red values could be different in you case. Note the dns-nameservers 8.8.8.8 8.8.4.4 - it says to use Google Public DNS. You can change it with simple command - sed.

  1. sed -i '/dns-nameservers 8.8.8.8 8.8.4.4/c\ dns-nameservers 1.2.3.4 1.2.3.5' /etc/network/interfaces

You can learn more about sed at GNU docs Change red values in command to reflect your desired DNS settings. After you execute it, it will change values. When you open /etc/network/interfaces you will notice changes.

You can also use this as User data on Droplet Creation:

#!/bin/bash

sed -i '/dns-nameservers 8.8.8.8 8.8.4.4/c\        dns-nameservers 1.2.3.4 1.2.3.4' /etc/network/interfaces

Note: this applies for DigitalOcean Ubuntu 16.04 droplets. If you use another host, or using it on your own machine, /etc/network/interfaces could be different and can cause command to fail!

Want to learn more? Join the DigitalOcean Community!

Join our DigitalOcean community of over a million developers for free! Get help and share knowledge in Q&A, subscribe to topics of interest, and get courses and tools that will help you grow as a developer and scale your project or business.

This comment has been deleted

Tell me please, when you change DNS, can also change my ip address? Or two of these parameters are not interrelated?