How to save the packages received by a network interface or some port in a file and resend the packages received when needed?

[Emile van Sebille]

On 8/31/2011 6:35 AM king6cong at gmail.com said...
> hi,
>    This is a question not specific to Python,but its related somehow,and
> I believe I can get some help from your fellow:)
>    I am doing my work on a server service program on Linux that
> processes the packages sent to the socket it listens.Their is already a
> old such service listening on the port doing its job,and
> I can't stop the old server service, and I need to get the packages sent
> to the old server and send them to my new server service to make sure it
> works well .How can I get the package and resent them to my new service?
> Is there such a tool or is there some functionality that tools such as
> tcpdump already provides?

I recently set up a standby spare fax server on a network that I also 
needed to test, and was able to tee the source transmissions to both 
systems.  That may be an option, particularly as it sounds like you've 
written a consumer of info and are not replying and interacting with the 
source.

Emile