If a particular IP was blacklisted due to certain reasons like more number of failed login attempts, suspicious activity, etc .., you can whitelist that IP and also if you want to blacklist an IP address you can do it in WHM.
1. Login into WHM.
2. Select “Security Center” from the list of options.
3. In “Security Center” section, Select “ cPHulk brute force protection”.
4. Select “Whitelist Management” Option and enter the IP you need to Whitelist, you can also add comment while listing the IP for your reference.
5. In order to blacklist an IP, the same procedure for whitelisting by selecting “Blacklist Management” option.