In packet-switched networks, devices may form connections to each other by transmitting packets which are received by other connected devices. In accordance with packet-based protocols, once a connection is established between two devices it remains defined until it's disconnected. After establishment and before disconnection packets can be exchanged between the devices, known as endpoints, within the context of the packet-based connection. An example of a packet-based protocol is the transmission control protocol, TCP.
Devices connected to the internet experience frequent unsolicited attempts to form connections. The unsolicited attempts may originate from automatic or malicious programs that seek access to the connected devices and owners of connected devices typically strive to reject or disconnect such attempts.
Connected devices or nodes in a network may be furnished with firewalls configured to filter traffic according to various programmable parameters. Firewalls may be programmed to block unsolicited traffic when characteristics of such traffic are known, and blocking such traffic in the network provides the advantage that the end node doesn't need to receive it.
Where the connected devices are mobile devices, all traffic and connections may be communicated using electromagnetic waves and both reception and transmission consume battery power, which may be a limited resource. Thus in mobile connected devices battery drain is a further reason for owners to try to limit the impact of unsolicited attempts to form connections to their devices. Mobile communication networks define wireless bearer protocols, such as packet data protocol contexts, PDP contexts, to convey packet-based data to and from wireless communication devices.
Some mobile devices are capable of communicating according to more than one wireless protocol, for example via a cellular and a wireless local area network, WLAN, connection. Other examples of wireless protocols include Bluetooth, WiMAX and Wibree protocols which are each adapted for packet-based communication.