The programmable resources of reconfigurable computing architectures are commonly used to support application specific processing. Dynamic reconfiguration enables hardware adaptation even during run-time. This paper concentrates on extending the application of dynamically reconfigurable logic to the area of network interface logic. The benefits and consequences of implementing even low-level networking functions in programmable hardware over fixed realizations are explained, and the possibilities arising from reconfigurable network interfaces are shown. Concerning reconfiguration of the network interface subsystem at run-time, maintaining connections, preventing packet loss, and guaranteeing response times during reconfiguration is crucial. Methods for dynamically replacing network interface hardware are described, and the current prototype is shown.