You will need to run these commands as 'root'.
This command blocks IP "18.104.22.168" at the firewall.
iptables -I INPUT -s 22.214.171.124 -j DROP
This command lists all the IPs currently blocked at the firewall
iptables -L INPUT -n --line-numbers
This command would remove line #3 from the firewall
iptables -D RH-Firewall-1-INPUT 3
This command saves the changes to the firewall