一直用CentOS 6 习惯了，一下没适应过来。防火墙配置后执行service iptables save 出现"Failed to restart iptables.service: Unit iptables.service failed to load: No such file or directory."错误,在CentOS 7或RHEL 7或Fedora中防火墙由firewalld来管理，当然你可以还原传统的管理方式。或则使用新的命令进行管理。
假如采用传统请执行一下命令：    
systemctl stop firewalld
systemctl mask firewalld
并且安装iptables-services：
yum install iptables-services
设置开机启动：

systemctl enable iptables

systemctl [stop|start|restart] iptables
#or

service iptables [stop|start|restart]

service iptables save
#or
/usr/libexec/iptables/iptables.init save

查看所有

[root@test ~]# iptables -nv -L

3、添加好之后防火墙规则如下所示：
###################################### 
# Firewall configuration written by system-config-firewall 
# Manual customization of this file is not recommended. 
*filter 
:INPUT ACCEPT [0:0] 
:FORWARD ACCEPT [0:0] 
:OUTPUT ACCEPT [0:0] 
-A INPUT -m state –state ESTABLISHED,RELATED -j ACCEPT 
-A INPUT -p icmp -j ACCEPT 
-A INPUT -i lo -j ACCEPT 
-A INPUT -m state –state NEW -m tcp -p tcp –dport 22 -j ACCEPT 
-A INPUT -m state –state NEW -m tcp -p tcp –dport 80 -j ACCEPT 
-A INPUT -j REJECT –reject-with icmp-host-prohibited 
-A FORWARD -j REJECT –reject-with icmp-host-prohibited 
COMMIT 
#####################################

防火墙2