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

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  Re: How to save the packages received by a network interface or some port in a file and resend the packages received when needed? Matty Sarro <msarro@gmail.com> - 2011-08-31 10:22 -0400
    Re: How to save the packages received by a network interface or some port in a file and resend the packages received when needed? Grant Edwards <invalid@invalid.invalid> - 2011-08-31 14:36 +0000

#12478 — Re: How to save the packages received by a network interface or some port in a file and resend the packages received when needed?

Its possible using TCPDUMP and wireshark. however its a bit of a
manual process (open the pcap in wireshark, select the correct tcp
stream, and extract the file). I did this to show a vulnerability in
how medical images were transmitted in a university hospital once :)

Here are some guides, maybe it can serve as a jumping off point?
http://packetlife.net/blog/2009/jul/13/quick-packet-capture-data-extraction/
http://wiki.wireshark.org/TCP_Reassembly

There are some C# libraries specifically for this:
http://www.codeproject.com/KB/IP/TcpRecon.aspx

Not sure if anything exists explicitly for python though.
-Matty

On Wed, Aug 31, 2011 at 9:35 AM, king6cong@gmail.com
<king6cong@gmail.com> wrote:
> 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?
> Thanks:)
>
> --
> http://mail.python.org/mailman/listinfo/python-list
>
>

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#12480

On 2011-08-31, Matty Sarro <msarro@gmail.com> wrote:

> Its possible using TCPDUMP and wireshark. however its a bit of a
> manual process (open the pcap in wireshark, select the correct tcp
> stream, and extract the file).

Presumably the OP knows the port IP address and port number on which
the server is listening, so wouldn't it be simpler to just capture TCP
traffic to/from that IP/port?

Then you can play it back using tcprewrite, tcpreplay, et al.

But, I don't see how that's going to work.  The OP seems to want to
capture a TCP session and then "replay it" so that the client from the
session ends up talking to a different server during the replay. The
chances of the new server starting up a connection with the same ACK
sequence number is practially nil isn't it?

>> ?? 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? Thanks:)

-- 
Grant Edwards               grant.b.edwards        Yow! ... this must be what
                                  at               it's like to be a COLLEGE
                              gmail.com            GRADUATE!!

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