1. A method comprising: generating a request message, with a trusted network entity executing trusted code on a first network layer, the request message to target a non-trusted network entity executing non-trusted code, on a second network layer; transmitting the request message from the trusted network entity to the non-trusted network entity through at least a policy enforcement entity, wherein the policy enforcement entity applies one or more network traffic rules to enforce a unidirectional flow of traffic from the first network layer to the second network layer; generating a response check message with the trusted network entity, the response check message to determine whether response information is available on the non-trusted network entity in response to the request message; and transmitting the response check message from the trusted network entity to the non-trusted network entity through at least the policy enforcement entity, the response check message to determine whether the response information is stored in a conceptual mailbox on the non-trusted network entity.