Using CSF it is possible to block/whitelist and IP address. Also, we can block traffic from a country.

Whitelisting an IP Address in CSF:

Use Quick Allow

• The Quick Allow option will allow the IP address access to all ports.
• Navigate to the ‘CSF – Quick Actions‘ section on the Security page.
• Enter the IP address you’d like to allow. This will allow the IP address through all ports.
• Click on Quick Allow to allow the IP address.

Use Quick Ignore

• Enter the IP address in the Quick Ignore section of CSF.
• Warning: Only use this setting for trusted IP addresses.
• Click Quick Ignore to allow the IP address through your firewall.

Blocking an IP in CSF:

Use Quick Deny

• Scroll down to the box saying, Quick Deny.
• This button should have a text field to the left of it. This is the option you want to use for blocking an IP.
• Input the IP you want to block in the field.
• Click Quick Deny to apply the block.

Unblocking an IP in CSF:

Use Quick Unblock

• Scroll down to the box saying Quick Unblock.
• This button should have a text field to the left of it. This is the option you want to use to unblock an IP.
• Input the IP you want to unblock in the field.
• Click quick unblock to remove the block.