Controlling passage of packets or messages via a virtual connection or flow

Passage of packets or messages is controlled between a device and a network via a virtual connection or flow which conforms to a predefined communication protocol. In connection with processing a packet or message that triggers a step in managing the virtual connection or flow, predefined authorization rules are applied to determine whether to permit the step to occur. In connection with processing a packet or message that does not trigger a step in managing the virtual connection or flow, the packet or message is permitted to pass directly via the virtual connection or flow, without applying the predefined authorization rules.