Centos 7 关闭邮件服务及禁用IPv6

关闭邮件服务（禁用25端口）

sudo systemctl stop dovecot
sudo systemctl stop postfix
sudo systemctl disable dovecot
sudo systemctl disable postfix

关闭 IPv6

vim /etc/default/grub

#命令中增加 ipv6.disable=1
GRUB_CMDLINE_LINUX="ipv6.disable=1 xxxxxxxx"

#生成新的配置文件并重启
grub2-mkconfig -o /boot/grub2/grub.cfg
reboot

参考博文:
https://www.crifan.com/centos_disable_email_services_dovecot_postfix/
http://blog.csdn.net/bluishglc/article/details/41390785