1. An apparatus comprising: a computing device located in a trusted network, the computing device executing a network management system, the computing device comprising: at least one processor; and a memory storing instructions that, when executed, cause the at least one processor to: access network information from the trusted network; access network information from an untrusted network; correlate one or more data flows in the trusted network to one or more encrypted data tunnels in the untrusted network to form fused network information; and generate a cross-domain network topology for the trusted network and the untrusted network based on the fused network information.