Whenever you have a device facing the Internet, you should ensure you have some basic protection against script kiddies, port scanners, and pinging apps.
In this example, I show you how to create a WAN port filter for a Ubiquiti EdgeRouter.
Nothing can take the place of a proper firewall, but this is always a good compromise if the firewall will be installed later .
Here is the link to the Ubiquiti article:
