The disclosed embodiments provide a system that processes incoming network packets to an electronic device. The system includes an analysis apparatus that maintains a list of accepted incoming packet attributes for the electronic device based on outgoing packets from the electronic device. The system also includes a filtering apparatus that compares a first set of header information for an incoming packet to the list. If the first set of header information is not included in the list, the filtering apparatus discards the incoming packet. If the first set of header information is included in the list, the filtering apparatus enables subsequent processing of the incoming packet on the electronic device by, for example, providing the incoming packet to a transport-layer mechanism on the electronic device for subsequent processing of the incoming packet by the transport-layer mechanism.