Sata Sengupta will present his FPO "Network-Boosted Applications" on Friday, April 3, 2026 at 1pm in CS 402. The members of his committee are as follows: Examiners: Jennifer Rexford (adviser), David Walker, Maria Apostolaki (ECE) Readers: Ravi Netravali, Hyojoon Kim (University of Virginia, CS) Zoom link: [ https://princeton.zoom.us/j/2332835952?pwd=tYVB2ta8EI4aC3eX4biZCbu4VyYK0J.1 | https://princeton.zoom.us/j/2332835952?pwd=tYVB2ta8EI4aC3eX4biZCbu4VyYK0J.1 ] Abstract follows below: Modern Internet applications such as video conferencing, cloud gaming, and AR/VR demand high media quality, low latency, and massive scale. Yet networks still operate largely as best-effort conduits with limited visibility into application behavior or quality of experience (QoE), leaving operators unable to react in time to short-lived congestion or stealthy attacks that disproportionately affect application performance or security. Addressing these problems requires packet-level measurement and real-time control in the network itself, where traffic can be observed and acted upon before users feel the impact. High-speed programmable switches and Smart Network Interface Cards (SmartNICs) offer a path to "boosting" applications at up to terabit rates, but only with careful designs that operate within stringent limits on memory and computation, while handling sophisticated, stateful protocols such as Transmission Control Protocol (TCP) for on-demand traffic (for example, web browsing and video streaming) and Real-Time Communication (RTC) for real-time interactive traffic (for example, video conferencing and online gaming). This dissertation develops efficient, hardware-amenable techniques for real-time network monitoring and control across both traffic classes. For on-demand traffic, we present DART (Data-plane Actionable Round-trip Times), which measures TCP round-trip time (RTT) at line rate by carefully handling retransmissions, reordering, and selective acknowledgments---TCP behaviors that can otherwise distort RTT samples or exhaust limited switch memory. Building on this capability, we develop HiDe (Hijack Defense) to promptly detect and mitigate stealthy long-distance routing attacks using passively monitored RTT variation as the detection signal. For interactive traffic, we analyze representative video-conferencing systems, including Zoom (proprietary) and MediaSoup (open-source), and derive detailed packet-level performance metrics. For Zoom, we show that despite encryption and a proprietary RTC protocol, packet headers retain enough information to recover per-media-stream quality indicators such as bitrate, frame rate, and jitter. These insights motivate Scallop, a scalable hardware-software co-designed architecture for video-conferencing infrastructure inspired by Software-Defined Networking (SDN). In Scallop, a high-speed data plane executes high-frequency, latency-sensitive operations, while a lean software control plane handles infrequent tasks, improving performance and scalability, and reducing cost relative to conventional software solutions. Overall, this dissertation advances scalable, application-aware network monitoring and control techniques that improve the performance and security of the Internet’s two most prevalent application classes. Our research artifacts, including hardware prototypes and traffic-analysis tools, are already being used by both academia and industry for further study and development.