In the current Internet, there is no clean way for affected parties to react to poor forwarding performance: to detect and assess Service Level Agreement (SLA) violations by a contractual partner, a domain must resort to ad-hoc monitoring using probes. Instead, we propose "Network Confessional," a new, systematic approach to the problem of forwarding-performance verification. Our system relies on voluntary reporting, allowing each network domain to disclose its loss and delay performance to its customers and peers and, potentially, a regulator. Most importantly, it enables verifiable performance measurements, i.e., domains cannot abuse it to significantly exaggerate their performance. Finally, our system is tunable, allowing each participating domain to determine how many resources to devote to it independently (i.e., without any inter-domain coordination), exposing a controllable trade-off between performance-verification quality and resource consumption. Our system comes at the cost of deploying modest functionality at the participating domains' border routers; we show that it requires reasonable resources, well within modern network capabilities.