To start dropping all incoming and outgoing packets, enter the following command as root:

~]# firewall-cmd --panic-on

All incoming and outgoing packets will be dropped. Active connections will be terminated after a period of inactivity; the time taken depends on the individual session time out values.

To start passing incoming and outgoing packets again, enter the following command as root:

~]# firewall-cmd --panic-off

After disabling panic mode, established connections might work again if panic mode was enabled for a short period of time.

To get a text indication if panic mode is enabled or disabled, enter the following command:

~]$  firewall-cmd --query-panic && echo "enabled" || echo "Not enabled"