Detecting stations cheating on backoff rules in 802.11 networks using sequential analysis

Abstract

As the commercial success of the IEEE 802.11 protocol has made wireless infrastructure widely deployed, user organizations are increasingly concerned about the new vulnerabilities to their networks. While various security issues have been extensively studied, the threats posed by denial-of-service (DoS) attacks have not been fully exploited. In this paper, we consider DoS attacks posed by cheating on the backoff rules in the IEEE 802.11 DCF protocol and propose a scheme detecting such adversaries. Our scheme is based on the sequential hypothesis testing. We first develop analytical models for packet interarrival time distribution from each station in the network where multiple cheating stations co-exist. Using the characterization of this probability distribution, we develop an algorithm to detect cheating stations based on the throughout degradations observed at normal stations. Our simulation results show that the proposed algorithm only requires very small number of observations of packets with very small value (i.e., less than 0.1%) of false positive and false negative decisions. That is, our proposed algorithm performs significantly fast and also accurately. © 2006 IEEE.