1. Search for ‘firewall, and click ConfigServer Secuirty&Firewall
2. There are three options that are very important: Quick Allow, Quick Deny, and Quick Ignore. You simply input an IP to the appropriate field.

Quick Allow will add an IP address to iptables’ allow list
Quick Deny will add an IP address to iptables’ deny list
Quick Ignore is managed by Login Failure Daemon (LFD). It will automatically block an IP address that make repeated failed attempts to login

Note:

If you have both IP address in Quick Allow & Quick Deny, It will deny the IP since Quick Deny has higher priority over Quick Allow

When adding an IP address to the allow list, it is highly recommended to add it to the ignore list at the same time