centos7 没有iptables 生成

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


service iptables save

service iptables restart

iptables -A  INPUT -p tcp --dport 21 -j ACCEPT
iptables -A OUTPUT -p tcp --sport 21 -j ACCEPT