helps from:
vi /etc/sysctl.conf net.ipv6.conf.all.disable_ipv6 = 1 net.ipv6.conf.default.disable_ipv6 = 1 sysctl -p
P.S
CentOS7中禁用IPV6
原文：http://www.cnblogs.com/flowjacky/p/5357643.html
