Disable IPv6

sysctl utility

Temporary

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

Permanent

Add into /etc/sysctl.conf:

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

Save and exit. Run sysctl -p to update.

To re-enable the IPv6, the process is the same as above except that instead of 1 keep it as 0.

GRUB

1. Open the GRUB file using command line text editor.

nano /etc/default/grub

2. Add ipv6.disable=1 in the following part. Save and exit.

GRUB_CMDLINE_LINUX_DEFAULT=”ipv6.disable=1 quiet splash”
GRUB_CMDLINE_LINUX=”ipv6.disable=1″

3. Update the GRUB.

update-grub

To re-enable the IPv6, undo the modifications made in the GRUB file.