Default Security Options on Meraki MX devices?

Hi all,

So I'm in the process of rebuilding the network to work with our new hardware, and the main thing I'm wondering(from a security standpoint) is if there is any security really seen from an MX security appliance right out of the box? Looking at the firewall settings it seems everything is allowed in and out of the network by default, which leads me to believe that it's not; but I was wondering if anyone might be able to share any tips to tighten up security easily? My main concern is locking everything down by only allowing certain traffic out/in, but we have a few unique vendors/items at some locations that will probably need to traverse the network that I don't have full knowledge of and cannot test in our lab environment. Any ideas on how to make this process easier? If the end result needs to be me only allowing certain traffic through, that's fine, however I was hoping there was an easier way to block most incoming traffic, and allow all outgoing traffic.

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Thanks!