I want to match all Linux system,

Centos, ubuntu, the best versions are available,
I mainly use centos 7. But it's also useful 6, two services are different, systemctl and service,
Is how to determine the iptables or firewalld,

or what command?

 
# general control 
The function firewall_port {
# judgment is iptables or firewalld, call different function, add port/service 
} 

The function firewalld_port {
# if the judgment is systemctl or service, to operate the service 
} 

The function iptables_port {
# with ipv6, that can support the best, don't support it doesn't matter, anyway, there are few use the 
}