Objective 1: Large Scale, Semantic-Rich Data Collection. First, AntMonitor is compatible with Android OS versions 4.0+, which makes it work with more than 94%ofAndroid devices today [4]. Second, AntMonitor is carefully designed to scale and supports tens of thousands of users [5]. Third, AntMonitor collects packet traces in PCAP Next Generation format [6], which allows the system to collect arbitrary information alongside with the raw packets, such as the names of applications that are associated with packets. Such information is only available at the client side, and yet it plays a critical role in subsequent analyses by providing ground truth for application classification. Fourth, AntMonitor is designed to provide maximumuser comfort: it runs seamlessly in the background, does not require a rooted phone, and most importantly, has modest CPU and battery usage while maintaining high network performance [5]. Last, AntMonitor entices users by providing privacy protection as discussed next. Objective 2: Enhanced User Privacy. First, to address privacy concerns in data collection, such as those discussed in the Menlo report [7], AntMonitor is designed to provide users with complete control over what data they may want to contribute. In particular, they can choose specific applications, and either full packets or just packet headers to contribute. Second, AntMonitor is able to