I need to simulate network latency to a program running on the local computer, connecting to a local service. Thus far I have tried dummynet (a windows build of ipfw) which I got working after some trial and error. While it generally works, I can't seem to get it to filter localhost traffic. Even after adding a rule from any to any which affects external traffic, this makes no difference for local connections. I would appreciate if anyone knows how to simulate local latency using dummynet or a different tool. The tool should be able to simulate latency generically in IP packets, (TCP and UDP) and not be protocol specific.