如何在CentOS 7中彻底关闭IPv6（2018.6.25日验证）

原文地址

查看服务监听的IP中是否有IPv6格式的地址

netstat -tuln

如果有tcp6协议的就是有打开ip6

编辑/etc/default/grub，在GRUB_CMDLINE_LINUX加上的后面句首加上ipv6.disable=1。 
修改前:

[root@localhost Desktop]# cat /etc/default/grub 
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="rd.lvm.lv=centos/root rd.lvm.lv=centos/swap rhgb quiet"
GRUB_DISABLE_RECOVERY="true"

修改后：

[root@localhost Desktop]# cat /etc/default/grub 
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="ipv6.disable=1 rd.lvm.lv=centos/root rd.lvm.lv=centos/swap rhgb quiet"
GRUB_DISABLE_RECOVERY="true"

修改完毕后保存，运行grub2-mkconfig -o /boot/grub2/grub.cfg重新生成grub.cfg文件。

[root@localhost Desktop]# grub2-mkconfig -o /boot/grub2/grub.cfg 
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-3.10.0-514.2.2.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-514.2.2.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-327.36.3.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-327.36.3.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-327.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-327.el7.x86_64.img
Found linux image: /boot/vmlinuz-0-rescue-d885883cdb4944609bc5e3493dd2b680
Found initrd image: /boot/initramfs-0-rescue-d885883cdb4944609bc5e3493dd2b680.img
done

重启系统，查看ip6是否关闭。