CentOS 7 by default comes configured with a built in firewall: firewalld. This is great for general security, but not so hot when you want to access a control panel, such as Plesk running on port 8443. Connect via SSH and run the following commands to fix this. These commands open the ports for Plesk (8443) and its update daemon (8447):systemctl restart firewalld
firewall-cmd --zone=public --add-port=8443/tcp --permanent
firewall-cmd --zone=public --add-port=8447/tcp --permanent
firewall-cmd --reload
If you're using a panel other than Plesk, like cPanel, be sure to look up the correct ports to open for that panel.
If you wish to use your control panel's firewall instead, run systemctl disable firewalld and then activate the control panel firewall.
Otherwise, be sure to activate firewalld on startup and disable any default iptables rules:systemctl stop iptables
systemctl mask iptables
systemctl enable firewalld.service
