How to disable IPV6 on Ubuntu

This article was published on Feb 05, 2021

For the current session

First, we need to run ip a and check if we have a IPV6 running:

ip-a.png

If so, we can disable it by running:

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

Now we can ip a over again and see if inet6has been gone away.

When you restart your PC it'll be back.

Permanently

To do that permanently, we have to open our /etc/sysctl.conf and set the same values we've ran in the previous section:

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

Then we run sudo sysctl -p to take effect.

Forcing update sysctl on reboot

If rebooting it does not work, create a /etc/rc.local file and paste the following snippet:

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

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

exit 0

Now, make it executable with:

sudo chmod 755 /etc/rc.local

This will manually (during the boot) refresh our sysctl config.

Re-enabling IPV6

To undo all of that, we need to remove the /etc/rc.local file we've created and also remove the instructions we've added at /etc/sysctl.config.

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