As part of this work, we design, implement and evaluate the first system and mobile app for identifying traffic differentiation for arbitrary applications in the mobile environment (i.e., wireless networks such as cellular and WiFi, used by smartphones and tablets). The key idea is to use a VPN proxy to record and replay the network traf- fic generated by arbitrary applications, and compare it with the network behavior when replaying this traffic outside of an encrypted tunnel. We perform the first known testbed experiments with actual commercial shaping devices to validate our system design and demonstrate how it outperforms previous work for detecting differentiation. We released our app and collected differentiation results from 12 ISPs in 5 countries. We find that differentiation tends to affect TCP traffic (reducing rates by up to 60%) and that interference from middleboxes (including video-transcoding devices) is pervasive. By exposing such behavior, we hope to improve transparency for users and help inform future policies.
Our findings were published at IMC 2015. Check out [our paper] (https://people.cs.umass.edu/~phillipa/papers/traffic-diff_imc15.pdf) for more details!