The fluctuating performance of wireless and mobile networks has triggered the need for smart algorithms to assess the user perception, resulting from the quality of network services. While efforts have been done to model the user experience resulting from the network performance, there is still the need for practical methods to assess the user-perceived performance, in the real environment. In this work, we present a set of criteria to observe the user behavior on the Web, passively from the network-level. The criteria are based on the monitoring of TCP control flags and HTTP requests. Thus, information about user actions performed in the web browser can be inferred by monitoring the TCP termination flags and by keeping track of the HTTP requests. Along the way, we also present some anomalies observed in the TCP connection termination process, which may result in performance degradation of Web transfers.