http://stackoverflow.com/questions/24756240/how-can-i-use-iptables-on-centos-7
# sudo service iptables start
Redirecting to /bin/systemctl start iptables.service
Failed to issue method call: Unit iptables.service failed to load: No such file or directory.
With RHEL 7 / CentOS 7, firewalld was introduced to manage iptables. IMHO, firewalld is more suited for workstations than for server environments.
It is possible to go back to a more classic iptables setup. First, stop and mask the firewalld service:
systemctl stop firewalld
systemctl mask firewalld
Then, install the iptables-services package:
yum install iptables-services
Enable the service at boot-time:
systemctl enable iptables
Managing the service
systemctl [stop|start|restart] iptables
Saving your firewall rules can be done as follows:
service iptables save
or
/usr/libexec/iptables/iptables.init save How can i use iptables on centos 7 or fedora?
原文：http://www.cnblogs.com/lvfeilong/p/3454trdgfdg.html