I am planning a project that will have all traffic leaving and entering the outside interface encapsulated in a GRE tunnel, which will be terminated on an ASR1004 router. I would also like to use the Zone Based Firewall feature on the same router.
Basically, traffic would enter on the Tun interface, be de-encapsulated on the router and then have the router check it against the policy.
Can this be done? If so, is it just a case of adding the Tun interface to the outside zone?