Verify iptables Enabled

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  labels:
    machineconfiguration.openshift.io/role: master
  name: 75-master-iptables-enable
spec:
  config:
    ignition:
      version: 3.1.0
    systemd:
      units:
      - name: iptables.service
        enabled: true

This will enable the iptables service in all the nodes labeled with the "master" role.

Note that this needs to be done for each MachineConfigPool

For more information on how to configure nodes with the Machine Config Operator see the relevant documentation.