Disable IPv6 Ubuntu.md

Method 1 - Disable IPv6 using GRUB

Configure GRUB to pass kernel parameters at boot time. You’ll have to edit /etc/default/grub. Once again, make sure you have administrator privileges:

sudo nano /etc/default/grub

Now you need to modify GRUB_CMDLINE_LINUX_DEFAULT and GRUB_CMDLINE_LINUX to disable IPv6 on boot:

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

Save the file and run the update-grub command:

sudo update-grub

The settings should now persist on reboot.

Method 2 - Disable IPv6 using Sysctl

This only temporarily disables IPv6. The next time your system boots, IPv6 will be enabled again.

To use this method run following command on terminal

sudo sysctl -w net.ipv6.conf.all.disable_ipv6=1
sudo sysctl -w net.ipv6.conf.default.disable_ipv6=1
sudo sysctl -w net.ipv6.conf.lo.disable_ipv6=1

However, If you put a little effort you can make this method as permanently disables IPv6. To do that, you to modify /etc/sysctl.conf.

sudo nano /etc/sysctl.conf

Add the following lines to the file (ignore it, if already exist those line):

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

For the settings to take effect use:

sudo sysctl -p

Now, create (with root privileges) the file /etc/rc.local

sudo nano /etc/rc.local

And fill it with the following lines:

#!/bin/bash
# /etc/rc.local

/etc/sysctl.d
/etc/init.d/procps restart

exit 0

Now use chmod command to make the file executable:

sudo chmod 755 /etc/rc.local

What this will do is manually read (during the boot time) the kernel parameters from your sysctl configuration file.

Re-enable IPv6

GRUB

If you modified the kernel parameters in /etc/default/grub, go ahead and delete the added options:

sudo nano /etc/default/grub

Now you need to modify GRUB_CMDLINE_LINUX_DEFAULT and GRUB_CMDLINE_LINUX to re-enable IPv6 on boot:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX=""

Now do:

sudo update-grub

Sysctl

if you modified /etc/sysctl.conf you can either remove the lines you added or change them to:

net.ipv6.conf.all.disable_ipv6=0
net.ipv6.conf.default.disable_ipv6=0
net.ipv6.conf.lo.disable_ipv6=0

You can optionally reload these values:

sudo sysctl -p

you can remove /etc/rc.local:

sudo rm /etc/rc.local