解决方案 ：

在 Oracle Linux 7 中，iptables 服务替换为 firewalld 服务。
命令 iptables -L 将列出节点上的规则集。

# iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
ACCEPT all -- anywhere anywhere ctstate RELATED,ESTABLISHED
ACCEPT all -- anywhere anywhere
INPUT_direct all -- anywhere anywhere
INPUT_ZONES_SOURCE all -- anywhere anywhere
INPUT_ZONES all -- anywhere anywhere
ACCEPT icmp -- anywhere anywhere
REJECT all -- anywhere anywhere reject-with icmp-host-prohibited
Chain FORWARD (policy ACCEPT)
target prot opt source destination
DOCKER-ISOLATION all -- anywhere anywhere
DOCKER all -- anywhere anywhere
....

systemctl 命令将列出节点上运行的所有服务。
验证服务“iptables”不会恢复任何输出。
服务 iptables 替换为名称“firewalld”

# systemctl | grep -i iptables
# systemctl | grep -i firewall
firewalld.service            loaded active running   firewalld - dynamic firewall daemon

要检查服务的状态可以使用以下命令：

# systemctl status firewalld
firewalld.service - firewalld - dynamic firewall daemon
   Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled)
   Active: active (running) since Sun 2016-05-29 03:33:25 EDT; 3h 12min ago
 Main PID: 830 (firewalld)
   CGroup: /system.slice/firewalld.service
           └─830 /usr/bin/python -Es /usr/sbin/firewalld --nofork --nopid
Jan 29 03:33:25 geeklab systemd[1]: Started firewalld - dynamic firewall daemon.

可以通过以下命令停止服务，我们可以重新检查状态：

# systemctl stop firewalld
# systemctl status firewalld
firewalld.service - firewalld - dynamic firewall daemon
   Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled)
   Active: inactive (dead) since Sun 2016-05-29 06:47:03 EDT; 17s ago
  Process: 830 ExecStart=/usr/sbin/firewalld --nofork --nopid $FIREWALLD_ARGS (code=exited, status=0/SUCCESS)
 Main PID: 830 (code=exited, status=0/SUCCESS)
Jan 29 03:33:25 geeklab systemd[1]: Started firewalld - dynamic firewall daemon.
Jan 29 06:47:03 geeklab systemd[1]: Stopping firewalld - dynamic firewall daemon...
Jan 29 06:47:03 geeklab systemd[1]: Stopped firewalld - dynamic firewall daemon.

要在下次启动时禁用该服务（RHEL6 及更早版本中的 chkconfig），我们可以执行以下命令。
通过执行该命令，相关文件链接被删除，下次不再引用。

# systemctl status firewalld
firewalld.service - firewalld - dynamic firewall daemon
   Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled)
   Active: inactive (dead) since Sun 2016-05-29 06:47:03 EDT; 2min 26s ago
  Process: 830 ExecStart=/usr/sbin/firewalld --nofork --nopid $FIREWALLD_ARGS (code=exited, status=0/SUCCESS)
 Main PID: 830 (code=exited, status=0/SUCCESS)
Jan 29 03:33:25 geeklab systemd[1]: Started firewalld - dynamic firewall daemon.
Jan 29 06:47:03 geeklab systemd[1]: Stopping firewalld - dynamic firewall daemon...
Jan 29 06:47:03 geeklab systemd[1]: Stopped firewalld - dynamic firewall daemon.

如上面的输出所示，firewalld 服务处于启用模式，这意味着它将在下次启动时启动。
要禁用下次启动时启动，请使用以下命令：

# systemctl disable firewalld
rm '/etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service'
rm '/etc/systemd/system/basic.target.wants/firewalld.service'

再次验证状态，以确认服务处于禁用模式。

# systemctl disable firewalld
rm '/etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service'
rm '/etc/systemd/system/basic.target.wants/firewalld.service'
[root@geeklab ~]# systemctl status firewalld
firewalld.service - firewalld - dynamic firewall daemon
   Loaded: loaded (/usr/lib/systemd/system/firewalld.service; disabled)
   Active: inactive (dead)
Jan 29 03:33:16 geeklab systemd[1]: Starting firewalld - dynamic firewall daemon...
Jan 29 03:33:25 geeklab systemd[1]: Started firewalld - dynamic firewall daemon.
Jan 29 06:47:03 geeklab systemd[1]: Stopping firewalld - dynamic firewall daemon...
Jan 29 06:47:03 geeklab systemd[1]: Stopped firewalld - dynamic firewall daemon.

问题：

如何在 CentOS/RHEL 7 中启动或者停止 firewalld（早期版本的 iptables）？