US Patent 7990967 Firewall method and apparatus for industrial systems

The invention includes a method including the steps of specifying access control information for resources, for each first protocol packet transmitted on the network, intercepting the first protocol packet prior to a first protocol destination resource, examining embedded packet information to identify at least one of the intermediate path resources and the final destination resource, identifying the access control information associated with the identified at least one of the intermediate path resources and the final destination resource and restricting transmission of the first protocol packet as a function of the identified access control information.