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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.

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If you're just testing HTTP traffic the Fiddler Web Debugger is pretty easy to use. You just select the stream, flip to the AutoResponder tab, select "Add Rule", then right click on the rule and select "Set Latency".

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Sorry, it's not http traffic. – nitro2k01 Oct 17 '13 at 15:55
@nitro2k01 then you should edit your question and include the information so people don't need to go hunting in comments of answers to get all of the information. – Scott Chamberlain Oct 17 '13 at 16:47
I have edited the question now, but I would think that if people make extra assumptions about the question that are not mentioned in the post, that's their prerogative. – nitro2k01 Oct 17 '13 at 21:09

On windows 7 you should take at Clumsy:

clumsy makes your network condition on Windows significantly worse, but in a managed and interactive manner.

clumsy demo

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