How to Disable IPv6 in CentOS 7

Check Whether IPv6 is Enabled

You can check whether IPv6 is enabled on your CentOS 7.5 operating system with the following command:

ip a | grep inet6

To disable ipv6 in the running system :

echo 1 > /proc/sys/net/ipv6/conf/all/disable_ipv6

echo 1 > /proc/sys/net/ipv6/conf/default/disable_ipv6