I am a die hard fans of CentOS, and on every OS reinstall I always disable IPv6 first. Why do I do it? Simply because it doesn’t look nice with netstat -tulpen

So here is the quick and dirty way to disable IPv6 on CentOS:

echo install ipv6 /bin/true >> /etc/modprobe.d/modprobe.conf
vi /etc/sysconfig/network-scripts/ifcfg-eth0

add these two lines:

NETWORKING_IPV6=no
IPV6INIT=no

or.. you can add these lines too

net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.eth0.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1

simply reboot the system. That’s all.