A networked computing platform implements an opportunistic data communication method. The computing platform creates, at the instigation of at least one application executing on the platform, data packets for transmission over a network. The packets are created using a hierarchy of programs (‘stack’) implementing a corresponding hierarchical suite of network protocols each associated with a corresponding protocol data unit (PDU) that comprises protocol-control information for that protocol. The opportunistic communication method involves the platform waiting for creation of a packet to be instigated and thereupon setting a parameter in protocol-control information of the packet to a value indicative of a characteristic of the computing platform, this characteristic being one unconnected with functioning of the network protocols. A network monitoring method and a network administration method are also disclosed.