How to disable IPv6 on Ubuntu and Linux Mint

We are running out of IPv4, and IPv4 doesn’t come with any security. IPv6 is coming but IPv6 isn’t ready yet. Somtimes, connections get delay or completely fail until IPv6 is disabled. Systems with IPv6 enabled will prefer IPv6 connections over IPv4. If a system is misconfigured and/or malfunctioning with IPv6, that system will cause connectivity problems. So how to disable IPv6 on ubuntu, linux mint?

To check if IPv6 is enabled or disabled

$ cat /proc/sys/net/ipv6/conf/all/disable_ipv6

0 means it’s enabled and 1 is disabled.

To disable IPv6

$ su -
# nano /etc/sysctl.conf

and add these lines to sysctl.conf file

#disable ipv6

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

Save sysctl.conf file with new config, then reboot your system

# reboot

Check your system again

$ cat /proc/sys/net/ipv6/conf/all/disable_ipv6

Now you should see “1″ means IPv6 has been disabled on your system.