This paper explores the idea of integrating digital forensic capabilities into network infrastructures. Building a forensic system for wide area networks has generally been considered infeasible due to the large volume of data that potentially has to be processed and stored. However, it is opportune to revisit this problem in the light of recent advances in data streaming algorithms, the abundance of cheap storage and compute power and, more importantly, increased threats faced by networked infrastructures. This paper discusses the challenges involved in building reliable forensic systems for wide area networks, including the Internet itself. Also, it describes a prototype network forensic system that is currently under development.