Detection of side-channel communication in ad hoc networks using request to send (RTS) messages

Abstract

Wireless communication channels using the 802.11 protocol adopt the RTS/CTS mechanism to avoid collisions in the channel and to increase throughput. In a perfect scenario with no data loss, there exists a linear relationship between number of the valid frames received and the RTS received in the receiver. We propose a detection mechanism that keeps track of the rate of RTS per application data frames received where any deviation from its expected value could trigger an alarm for a possible sidechannel communication hidden by error frames. Several scenarios are simulated using QualNet simulator by varying the parameters to study the relationship between the good frames and the RTS. Based on the data collected we submit that this rate is a viable metric for detection.

Assessing the Viability of Performance Evaluation Methods in Network Research

“…It then proceeds to wait for a randomly determined length of time (backoff) before sending its data. After this waiting period, if no other station attempts to acquire access, the terminal may gain access in one of two ways: (1) The transmitting node transmits a request-to-send (RTS) packet [14] to the receiving terminal during the four-way handshake. When the request is accepted, the receiver sends a clear to send (CTS) packet.…”