A method for determining if a multiplicity of networks are authorized to communicate with each other and what IP protocol can be used for communication between each combination of two of the networks. For each network, a computer readable data base stores a record of (a) IP protocol(s) permitted to be used with said each network and (b) types of other networks permitted to communicate to said each network. For said each network, a computer readable data base stores a record of IP protocols and destination and source networks permitted by a respective firewall or router for said each network. For said each network, a computer readable data base stores a record of a type of said each network. Multiple combinations of the networks are automatically identified. Each of the combinations comprises a source network and a destination network. For each of the combinations, based on the records, it is automatically determined if each of the networks in the combination is permitted to communicate with the other network in the combination and what IP protocol(s) are common to both of the networks in the combination.