How To Disable IPv6 on Ubuntu 18.04 LTS

In this tutorial, we will show you how to disable IPv6 on Ubuntu 18.04 LTS. For those of you who didn’t know, In today’s interconnected world, Internet Protocol (IP) addresses play a crucial role in enabling communication between devices on networks. While IPv4 has been the dominant protocol for decades, the transition to IPv6 is gradually taking place. However, there are situations where disabling IPv6 on Ubuntu 18.04 LTS might be necessary.

This article assumes you have at least basic knowledge of Linux, know how to use the shell, and most importantly, you host your site on your own VPS. The installation is quite simple and assumes you are running in the root account, if not you may need to add ‘sudo‘ to the commands to get root privileges. I will show you the step-by-step disable IPv6 on an Ubuntu 18.04 Bionic Beaver server.

Prerequisites

• A server running one of the following operating systems: Ubuntu 18.04 Bionic Beaver.
• It’s recommended that you use a fresh OS install to prevent any potential issues.
• SSH access to the server (or just open Terminal if you’re on a desktop).
• A non-root sudo user or access to the root user. We recommend acting as a non-root sudo user, however, as you can harm your system if you’re not careful when acting as the root.

Disable IPv6 on Ubuntu 18.04 LTS Bionic Beaver

Step 1. First, make sure that all your system packages are up-to-date by running the following apt-get commands in the terminal.

sudo apt update
sudo apt upgrade

Step 2. Permanently Disable IPv6 on Ubuntu 18.04/16.04.

• Method 1: Disabling IPv6 Using sysctl

Another approach to disable IPv6 on Ubuntu 18.04 LTS is by using the sysctl command, which allows you to modify kernel parameters at runtime.

To disable IPv6 using sysctl, Open the Ubuntu terminal and Perform the following steps:

nano /etc/sysctl.conf

Add the following lines at the end of the sysctl.conf file:

net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1

In Ubuntu server 18.04 LTS, you will need to add additional lines for each interface you want to disable IPv6:

net.ipv6.conf.<ifname>.disable_ipv6 = 1

For change to be effected, run the sysctl -p command:

sysctl -p

• Method 2: Disabling IPv6 Using GRUB

One of the most effective ways to disable IPv6 on Ubuntu 18.04 LTS is by modifying the GRUB bootloader configuration. This method ensures that IPv6 is disabled system-wide and persists across reboots.

Perform the following steps with root privileges to disable IPv6 in the Ubuntu system Permanently using the grub method.

Open the /etc/default/grub, Modify GRUB_CMDLINE_LINUX and GRUB_CMDLINE_LINUX_DEFAULT to append ipv6.disable=1:

GRUB_CMDLINE_LINUX="ipv6.disable=1"
GRUB_CMDLINE_LINUX_DEFAULT="ipv6.disable=1"

Update the grub configuration:

update-grub

Reboot the server:

systemctl reboot

Congratulations! You have successfully disabled IPv6. Thanks for using this tutorial for disabling IPv6 on your Ubuntu 18.04 Bionic Beaver system. For additional help or useful information, we recommend you check the official UFW Firewall website.