Telltale Twin: Mutual Information in Multipath TCP Subflows

Abstract

Multipath Transmission Control Protocol (MPTCP) uses multiple subflows through multiple interfaces to create a single network connection between two hosts. Because of the internal control signals, such as data sequence numbers used in the MPTCP header, there is an opportunity for an observer in one subflow to get network related information of the unseen subflow. If the observer observes some gaps in the data sequence numbers, we can assume that the missing sequence data numbers are sent through the unseen subflow. Based on this phenomenon, a hypothesis can be made that by observing one subflow, some network related information about the unseen subflow can be inferred. To prove the hypothesis some experiments were conducted using a virtual network setup.