How do I add a network interface to firewalld?

To add the ens18 interface to the public zone of firewalld in Linux, you can follow these steps:

Open a terminal on your Linux machine.
Check the current zones and the configured interfaces using:
```
sudo firewall-cmd --get-active-zones
```
Add the ens18 interface to the public zone with the following command:
```
sudo firewall-cmd --zone=public --add-interface=ens18 --permanent
```
The --permanent option ensures that the change persists after a reboot.
Reload the firewall to apply the changes:
```
sudo firewall-cmd --reload
```
Verify that the interface has been added to the public zone:
```
sudo firewall-cmd --zone=public --list-interfaces
```

You should see ens18 listed as part of the public zone. If you have any further questions or need assistance with anything else, feel free to ask!