As enterprises move to a cloud-rst approach, their network becomes crucial to their daily operations and has to be continuously monitored. Although passive monitoring can be convenient from a deployment viewpoint, inferring the state of each connection can cause them to miss important information (e.g., starvation). Furthermore, the increasing usage of fully encrypted protocols (e.g., encrypts headers), possibly over multiple paths (e.g.,), keeps diminishing the applicability of such techniques to future networks.We propose a new monitoring framework, Flowcorder, which leverages information already maintained by the endhosts and records Key Performance Indicators ( s) from their transport protocols. More speci cally, we present a generic approach which inserts lightweight e probes at runtime in the protocol implementations. These probes extract s from the per-connection states, and eventually export them over for analysis. We present an application of this technique to the Linux kernel stack and demonstrate its generality by extending it to support . Our performance evaluation con rms that its overhead is negligible. Finally, we present live measurements collected with Flowcorder in a campus network, highlighting some insights provided by our framework.Problem statement How can we support the legitimate need of ne grained performance information from enterprise network operators in presence of encrypted, multipath protocols? Key challenges Designing a monitoring framework that answers this question raises at least four challenges. First, this framework must accurately depict the performance experienced by the end-hosts. This limits the applicability of active measurements, as this might hide issues speci c to 1