# firewall-cmd --permanent --zone=drop --add-source=3.3.3.0/24
# firewall-cmd --reload

firewall-cmd --list-all --zone=drop
drop (active)
  target: DROP
  icmp-block-inversion: no
  interfaces:
  sources: 3.3.3.0/24
  services:
  ports:
  protocols:
  masquerade: no
  forward-ports:
  source-ports:
  icmp-blocks:
  rich rules: