This article has been kept here for link continuity purposes but the Firewall module no-longer contains an IP manual black list feature.
The current IP Management facility can be see here: https://icontrolwp.freshdesk.com/support/solutions/folders/3000007542
The Blacklist should be used sparingly and with great caution.
Any IP address found on this list will be completely blocked from accessing any page on your WordPress site.
We recommend that unless you have a very specific need for it, you should leave this option entirely empty. It is provided here as a convenience.
You could use it for example to block web services that you no longer wish to connect to your site.