Firewall

Blocking an IP Address

iptables -t filter -I INPUT -s 1.2.3.4/32 -j DROP

or

firewall-cmd \
--direct \
--add-rule ipv4 filter INPUT_direct 0 -s 1.2.3.4/32 -j DROP

or permanantly

firewall-cmd \
 --permanent \
--direct \
--add-rule ipv4 filter INPUT_direct 0 -s 1.2.3.4/32 -j DROP