首先需要说明的是CentOS7使用的是firewalld.service，而不是iptables.service
[xf@xuexi ~]$ systemctl status firewalld.service //查看防火墙状态
● firewalld.service - firewalld - dynamic firewall daemon
Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; vendor preset: enabled) //红色标注的地方就是是否开机自启
Active: active (running) since 五 2018-09-07 14:00:58 CST; 18min ago
Docs: man:firewalld(1)
Main PID: 9907 (firewalld)
CGroup: /system.slice/firewalld.service
└─9907 /usr/bin/python -Es /usr/sbin/firewalld --nofork --nopid
9月 07 14:00:59 xuexi firewalld[9907]: WARNING: COMMAND_FAILED: '/usr/sbin/....
9月 07 14:00:59 xuexi firewalld[9907]: WARNING: COMMAND_FAILED: '/usr/sbin/....
9月 07 14:00:59 xuexi firewalld[9907]: WARNING: COMMAND_FAILED: '/usr/sbin/....
9月 07 14:00:59 xuexi firewalld[9907]: WARNING: COMMAND_FAILED: '/usr/sbin/....
9月 07 14:00:59 xuexi firewalld[9907]: WARNING: COMMAND_FAILED: '/usr/sbin/....
9月 07 14:00:59 xuexi firewalld[9907]: WARNING: COMMAND_FAILED: '/usr/sbin/....
9月 07 14:00:59 xuexi firewalld[9907]: WARNING: COMMAND_FAILED: '/usr/sbin/....
9月 07 14:00:59 xuexi firewalld[9907]: WARNING: COMMAND_FAILED: '/usr/sbin/....
9月 07 14:00:59 xuexi firewalld[9907]: WARNING: COMMAND_FAILED: '/usr/sbin/....
9月 07 14:00:59 xuexi firewalld[9907]: WARNING: COMMAND_FAILED: '/usr/sbin/....
Hint: Some lines were ellipsized, use -l to show in full.
[xf@xuexi ~]$ systemctl stop firewalld.service //关闭防火墙
[xf@xuexi ~]$ systemctl start firewalld.service //开启防火墙
[xf@xuexi ~]$ systemctl disable firewalld.service //关闭开机自启
Removed symlink /etc/systemd/system/multi-user.target.wants/firewalld.service.
Removed symlink /etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service.
[xf@xuexi ~]$ systemctl enable firewalld.service //打开开机自启
Created symlink from /etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service to /usr/lib/systemd/system/firewalld.service.
Created symlink from /etc/systemd/system/multi-user.target.wants/firewalld.service to /usr/lib/systemd/system/firewalld.service.