Block All Traffic Except

We have a network set up strictly for an emergency system we use. Is there a way to block absolutely all traffic except what meets the one allow rule needed for the emergency system?

Yes, you can create policy for specific sources IP addresses.

  1. Allow specific destination from those system wanted to access using custom url categories.
  2. Deny all from those servers.

You can leverage firewal policies as well for otherthan web traffic.

Note that the GRE with sub location to be configured with those systems.