There are two levels of firewall for Cloud Server：
1) default firewall (firewallld, iptables, ufw) within your OS level, and
2) Cloud Server level firewall from our system.
If you want to use our Cloud Server level firewall, please login to client portal.
top menu > My Services > select relevant server > Firewall Options > click pencil icon on top left > toggle enable firewall.
3) after activate firewall,
top menu > My Services > select relevant server >click +Add button to add your firewall rules.
The firewall rule will take into effect within few seconds.