دانلود رایگان مقاله متراکم کردن مداوم در شبکه های محلی بی سیم

Abstract

Wireless local area networks (WLANs) can adopt channel hopping technologies in order to avoid unintentional interferences such as radars or microwaves, which function as proactive jamming signals. Even though channel hopping technologies are effective against proactive types of jamming, it has been reported that reactive jammers could attack the targets through scanning busy channels. In this paper, we demonstrate that reactive jamming is only effective against channel hopping WLAN devices in non-dense networks and that it is not effective in dense networks. Then, we propose a new jamming attack called “persistent jamming”, which is a modified reactive jamming that is effective in dense networks. The proposed persistent jamming attack can track a device that switches channels using the following two features, and it can attack the specific target or a target group of devices. The first feature is that the proposed attack can use the partial association ID (PAID), which is included for power saving in the IEEE 802.11ac/af/ah frame headers, to track and jam the targets. The second feature is that it is possible to attack persistently based on device fingerprints in IEEE 802.11a/b/g/n legacy devices. Our evaluation results demonstrate that the proposed persistent jamming can improve the attack efficiency by approximately 80% in dense networks compared with the reactive jamming scheme, and it can also shut down the communication link of the target nodes using 20 dBm of jamming power and a 125 ms response time. In order to defend against the persistent jamming attack, this paper proposes three defense mechanisms for anti-tracking and anti-jamming; a digital fingerprints predistortion, dynamic ID allocation, and dual channel friendly jamming. The experimental results demonstrate that the proposed defense mechanisms are feasible and effective to significantly decrease the device tracking success ratio of the persistent jamming attack.

6. Conclusion

In this paper, we examined the limitations of the existing jamming schemes against channel hopping WLAN devices in dense networks. Even though it is natural for malicious jammers to attempt to identify target nodes in dense networks, this has not been investigated in jamming attack scenarios thus far. Therefore, we proposed and developed a persistent jamming attack to track and jam the target devices based on the PAID and device fingerprints in the frame header. Furthermore, we evaluated the effectiveness of the jamming schemes through empirical experiments and demonstrated that persistent jamming can attack target nodes in dense networks even though they adapt the channel frequency to avoid jamming signals. The evaluation results confirm the superior effi- ciency of the persistent jamming strategy in a dense network environment in dense network conditions. Finally, we recommended effective anti-persistent jamming defense mechanisms to protect the PAID and device fingerprints. Almost all modern wireless communication systems have the same security limitation in the frame formats which have an unprotected frame header. For low latency and high efficiency, the frame headers are not encrypted in typical wireless systems. Thus, any device can decode the signal information and detect the device fingerprints. However, the frame headers of the modern wireless communication systems include more information for advanced wireless connectivity. If the frame header is not protected, a persistent jammer can track and jam, or an eavesdropper can track and overhear the communication. Therefore, in this paper, anti-tracking and anti-jamming defense mechanisms are proposed. The prototype experiment and network emulation results show that the proposed defenses are effective in mitigating harmful effects of the persistent jamming attack. As future work, we plan to apply the persistent jamming attack for other wireless networks to test the extendibility of its efficacy and investigate more efficient defense mechanisms against persistent jamming attacks in terms of complexity and defense performance.