To Disbale IPv6 for Linux:

CentOS 7.x

vi /etc/sysctl.conf

Add the line

net.ipv6.conf.all.disable_ipv6 = 1

Activate the changes without a reboot

sysctl -p

CentOS 6.x

vi /etc/sysconfig/network

NETWORKING_IPV6=no

vi /etc/modprobe.conf

alias net-pf-10 off
alias ipv6 off

Stop the ipv6tables service

service ip6tables stop
chkconfig ip6tables off