Presentation on theme: "Network security Dr.Andrew Yang. A wireless sensor network is network a consisting of spatially distributed autonomous devices using sensors to cooperatively."— Presentation transcript:
A wireless sensor network is network a consisting of spatially distributed autonomous devices using sensors to cooperatively monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion or pollutants, at different locations
Ease of installation, Self-identification, self-diagnosis, Reliability, time awareness for coordination with other nodes A smart sensor is a sensor that provides extra functions beyond those necessary for generating a correct representation of the sensed quantity
The wireless sensor network is susceptible to many attacks and so the simple cryptographic methods cannot be used. One such kind of an attack is denial of service attack where the adversaries observe the communication and send false messages so that wireless devices could not communicate.
802.11 control frames can be used to "busy out" a channel so that no other station can transmit. Entering this continuous transmit mode is known as a Queensland DoS attack. 802.11 deauthenticate frames can be used to disconnect an individual station, or every station. Sending a continuous stream of these forged frames is known as a Deauth Flood. Similar attacks can be launched using forged 802.1X packets -- for example, 802.1X EAP Logoff Flood, EAP Start Flood, and EAP-of-Death attacks.
As the 802.11b/g uses the crowded 2.4ghz band it is susceptible to interference from other radio waves is common like Bluetooth, cordless phones etc.
Use a WIDS to spot the appearance new devices that transmit 802.11 on the bands and channels used by your WLAN. Use WIDS alerts to flag over-loaded channel or excessive error or retransmission rates (possible non-802.11 interference). For non-802.11 interference sources, use a spectrum analyzer to monitor transmissions and fingerprint the type of device you should be looking for. Track down interference sources by using a WIDS to plot an approximate location. Then use a mobile tool to search that area and isolate the device's location 
Unlike traditional denial of service attacks, which are concerned with filling user domain and kernel domain buffers, jamming attacks exploit the shared nature of the wireless medium in order to prevent devices from communicating or receiving
Constant Jammer: continually emits a radio signal, and can be implemented using either a wave form generator that continuously sends a radio signal. Usually, the underlying MAC protocol allows legitimate nodes to send out packets only if the channel is idle. Thus, a constant jammer can effectively prevent legitimate traffic sources from getting hold of a channel and sending packets
It constantly injects regular packets to the channel without any gap between subsequent packet transmissions the normal communicator will be deceived into believing there is a legitimate packet and be duped to remain in the receive state. For example, in TinyOS, if a preamble is detected, a node remains in the receive mode, regardless of whether that node has a packet to send or not. Even if a node has packets to send, it cannot switch to the send state because a constant stream of incoming packets will be detected.
It doesn’t continuously try to jam it sleeps for some time and then it tries to jam when it is not in sleeping mode. During its jamming phase it can either behave as a constant or a deceptive jammer. This kind of attack is launched by an adversary who doesn’t have unlimited power supply.
The other three work irrespective of the traffic on the channel where as this jammer doesn’t do anything when the channel is idle but starts transmitting as soon as it detect an activity on the channel. This kind of jamming is hard to detect.
The first strategy involves avoiding the jammer in either the spectral or spatial sense, and can be achieved by changing channel allocations or, in mobile sensor networks, by moving nodes away from the jammer. The second strategy involves competing with the jammer by adjusting the transmission power levels and employing error correction in order to have more resilience against jamming
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