Redirecting network traffic within a system under test (SUT) can include receiving, within a proxy included within the SUT, a request sent from an upstream component that is directed to a downstream component, wherein the upstream component is configured to direct communications through the proxy. Within the proxy, the request can be redirected from the downstream component to a simulation component according to a routing rule within the proxy using a processor. A response can be received, within the proxy, from the simulation component and sent to the upstream component.