iptables
> service iptables status
> service iptables start
> service iptables stop
> service iptables restart
> chkconfig iptables off
> chkconfig iptables on
> vim /etc/sysconfig/iptables
-A INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT
> service iptables restart
firewall
> systemctl status firewalld
> service start firewalld
> systemctl unmask firewalld.service
> systemctl start firewalld.service
> systemctl stop firewalld
> firewall-cmd --query-port=80/tcp
> firewall-cmd --add-port=80/tcp --permanent
> firewall-cmd --reload
> firewall-cmd --remove-port=80/tcp --permanent