在CentOS7中，有很多CentOS 6中的常用服务发生了变化。
其中iptables是其中比较大的一个。防火墙iptables被firewalld取代。
本文将介绍，如果采用systemctl关闭firewalld，开启iptables。
1.关闭firewalld
[root@hwcentos70-01 system]# systemctl stop firewalld
[root@hwcentos70-01 system]# systemctl disable firewalld
[root@hwcentos70-01 system]# systemctl status firewalld
firewalld.service - firewalld - dynamic firewall daemon
Loaded: loaded (/usr/lib/systemd/system/firewalld.service; disabled)
Active: inactive (dead)
Feb 26 13:48:00 hwcentos70-01 systemd[1]: Stopped firewalld - dynamic firewall daemon.
Feb 26 13:48:14 hwcentos70-01 systemd[1]: Starting firewalld - dynamic firewall daemon...
Feb 26 13:48:15 hwcentos70-01 systemd[1]: Started firewalld - dynamic firewall daemon.
Feb 26 13:49:23 hwcentos70-01 systemd[1]: Started firewalld - dynamic firewall daemon.
Feb 26 13:53:18 hwcentos70-01 systemd[1]: Stopping firewalld - dynamic firewall daemon...
Feb 26 13:53:18 hwcentos70-01 systemd[1]: Stopped firewalld - dynamic firewall daemon.
2.开启iptables
首先安装iptables：
[root@hwcentos70-01 system]#yum install -y iptables-services
[root@hwcentos70-01 system]# systemctl enable iptables
ln -s '/usr/lib/systemd/system/iptables.service' '/etc/systemd/system/basic.target.wants/iptables.service'
[root@hwcentos70-01 system]# systemctl start iptables
[root@hwcentos70-01 system]# systemctl status iptables
iptables.service - IPv4 firewall with iptables
Loaded: loaded (/usr/lib/systemd/system/iptables.service; enabled)
Active: active (exited) since Fri 2016-02-26 13:54:45 UTC; 6s ago
Process: 55539 ExecStart=/usr/libexec/iptables/iptables.init start (code=exited, status=0/SUCCESS)
Main PID: 55539 (code=exited, status=0/SUCCESS)
Feb 26 13:54:45 hwcentos70-01 iptables.init[55539]: iptables: Applying firewall rules: [ OK ]
Feb 26 13:54:45 hwcentos70-01 systemd[1]: Started IPv4 firewall with iptables.
此时iptables的命令都可以使用了：
[root@hwcentos70-01 system]# iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
[root@hwcentos70-01 system]# service iptables save
iptables: Saving firewall rules to /etc/sysconfig/iptables:[ OK ]