Unblocking an IP Address in CSF
To find whether an IP address is blocked, please follow below steps.
Type ConfigServer Security & Firewall in the WHM search bar and go to that section.
Next use the Search for IP button on the ConfigServer Security&Firewall page. Simply enter the IP address into the search field and click the button.
If the IP address is blocked, the reason for the block will be listed and an unlocked padlock icon will appear to the right of the blocked IP address. Clicking the padlock icon will unblock the IP in the firewall. After that you need to restart the csf.
If it is not blocked output will be like in the below image.
Allowing (Whitelisting) an IP Address
It is important to note that there are two components to the csf firewall, the firewall itself and the Login Failure Daemon (lfd). To whitelist an IP address in the firewall (csf.allow), you can enter the IP address into the Quick Allow section and click the Quick Allow button.
It still can become blocked by lfd. You can prevent an IP address from being blocked by lfd by adding it to the ignore list (csf.ignore). That can be done using the Quick Ignore button on the ConfigServer Security&Firewall page. After this you need to restart lfd.