linux 下刚装入centos 防火墙情况。

1：检查是否安装iptables防火墙：

[root@localhost bin]# service iptables status
Redirecting to /bin/systemctl status  iptables.service
iptables.service
   Loaded: not-found (Reason: No such file or directory)

   Active: inactive (dead)

2：没有安装的话默认使用的是firewall作为防火墙,所以把他停掉，安装一个iptables

[root@localhost sysconfig]# systemctl stop firewalld 
[root@localhost sysconfig]# systemctl mask firewalld 
ln -s '/dev/null' '/etc/systemd/system/firewalld.service'
[root@localhost sysconfig]# yum install -y iptables    （安装iptables）
已加载插件：fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirrors.163.com
 * extras: mirrors.cn99.com
 * updates: mirrors.njupt.edu.cn
正在解决依赖关系
--> 正在检查事务
---> 软件包 iptables.x86_64.0.1.4.21-13.el7 将被 升级

---> 软件包 iptables.x86_64.0.1.4.21-24.1.el7_5 将被 更新

[root@localhost sysconfig]# systemctl start iptables.service
[root@localhost sysconfig]# systemctl enable iptables.service   //设置开机自启
ln -s '/usr/lib/systemd/system/iptables.service' '/etc/systemd/system/basic.target.wants/iptables.service'
[root@localhost sysconfig]# service iptables status  //状态
Redirecting to /bin/systemctl status  iptables.service
iptables.service - IPv4 firewall with iptables
   Loaded: loaded (/usr/lib/systemd/system/iptables.service; enabled)
   Active: active (exited) since 四 2018-07-12 23:58:08 CST; 47s ago
 Main PID: 17625 (code=exited, status=0/SUCCESS)

[root@localhost sysconfig]# vi /etc/sysconfig/iptables  //添加开放端口