Firewalld / iptables
on pew, i removed the iptables and engaged firewalld. These are firewalls that protect the server from unwanted incoming connections.
Check status (you cannot run iptables AND firewalld, but firewalld is recommended now to usurp iptables)
$ systemctl status iptables
Disable and mask iptables
$ sudo systemctl stop iptables
$ sudo systemctl mask iptables
Enable firewalld
$ systemctl enable firewalld
Start firewalld
$ systemctl start firewalld
open port for db