We will be disabling IPv6 in kernel module.
First, check IPv6 is enabled or not
ifconfig -a | grep inet6
if you see inet6 in the output, you have IPv6.
Let’s disable it. Edit /etc/default/grub file and add ” ipv6.disable=1″ to GRUB_CMDLINE_LINUX
GRUB_TIMEOUT=5 GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)" GRUB_DEFAULT=saved GRUB_DISABLE_SUBMENU=true GRUB_TERMINAL_OUTPUT="console" GRUB_CMDLINE_LINUX="crashkernel=auto rd.lvm.lv=centos/root rd.lvm.lv=centos/swap rhgb quiet" GRUB_DISABLE_RECOVERY="true" GRUB_CMDLINE_LINUX="ipv6.disable=1 crashkernel=auto rhgb quiet"
Recreate a GRUB configuration file with command:
grub2-mkconfig -o /boot/grub2/grub.cfg
Now we can restart the server and verify no line “inet6” in the ifconfig/ip command output.
init 6 ifconfig -a | grep inet6
Ok, that’s it!