If you are not familar with firewalld and the firewall-cmd, check out our Getting Started article.

Masquerade must be turned on to port forward. Use the --add-forward-port=port=xx:proto=xxx:toport=xx to forward traffic from one port to another. In this example, traffic is forwarded from TCP port 22 to port 12345. In this example, the SSH service listening on port 12345 is on the same server as the SSH service with port 22.

firewall-cmd --zone=external --add-forward-port=port=22:proto=tcp:toport=12345 --permanent

To forward request to another server, add the target IP address.

firewall-cmd --zone=external --add-forward-port=port=22:proto=tcp:toport=10.1.2.3:12345 --permanent

The --check-config command can be used to ensure there are no configuration errors.

~]$ firewall-cmd --check-config
success

firewall-cmd --list-all will show the forward ports.

~]# firewall-cmd --list-all
public
  target: default
  icmp-block-inversion: no
  interfaces: eth0
  sources:
  services:
  ports:
  protocols:
  masquerade: no
  forward-ports: 12345
  sourceports:
  icmp-blocks:
  rich rules: