need utillity that can do complex tcp replay

william(at) william at
Tue Dec 12 08:49:45 UTC 2006

I need to find utility for testing of application debugging issue that
can replay captured ip traffic, something similar to description at:

Basicly what I want is to capture data for several hours on the server 
(preferably with tcpdump) and then I'd like to replay requests that came 
to server from another computer that would act as a client and simulate
this traffic including using the same ip addresses as on the original 
captured packets, but all would be sent to different server which has
basically same setup & data as original but with debugging & testing
utilities (and with possibility to run application in debugging mode).
So what would be replayed would all be new TCP requests but contain 
same data as original and testing server would have direct 1-1
connection to a "simulated client" with this captured data and this
client would need to be able to replay TCP packets creating sequence
that is same order as original. Note that what I need to debug is
actually HTTPS which may present additional problems (including various 
timing issues since Expires header can not be rewritten without decoding 
encrypted data, but for that I'll reset time on the test server to be 
exactly same as it was when data was captured; but I'm sure there other 
other issues).

While I'd greatly prefer to find unix-based open-source package that
can do above, I'll consider other including commercial alternatives.
If you know of something that can do it, please reply.

William Leibzon
Elan Networks
william at

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