Re: [Tcpreplay-users] tcprewrite seed issues

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That is what I suspected.  I think my next best bet would be to split
them, check to make sure the connections are the same, then rewrite
however many times I need, then merge them back together.  Could a
solution could be to have multiple sets of seeds? 'seed A' for 2 seconds,
'seed B' for 2 seconds, etc...
Thanks for the quick response though, let me know if anyone has a better
suggestion for a workaround than what mine is above.

-----Original Message-----
From: Aaron Turner [mailto:syn...@gm...]
Sent: September-25-12 3:00 PM
To: Main forum for tcpreplay
Subject: Re: [Tcpreplay-users] tcprewrite seed issues

I can guess.  The randomization feature isn't that smart... just a simple
algorithm and doesn't check for uniqueness.  I never bothered to check
that it was a good implementation for large data sets.

http://tcpreplay.synfin.net/browser/branches/3.4/src/tcpedit/edit_packet.c
#L125

If you have enough packets with enough IP addresses, sooner or later
you'll end up with a collision (IP1 and IP2 => NewIP).   I guess I
could come up with a better algorithm which avoids duplicate results.
Probably be a while before that happens though.

On Tue, Sep 25, 2012 at 10:04 PM, Eric Formo <er...@vi...>
wrote:
> Using tcprewrite with the seed argument is not working for me right
> now.  I am rewriting 2.5G pcap that is about 7 seconds long with
> tcprewrite --seed=$(($RANDOM*$RANDOM)).  After rewriting, my pcap goes
> from having
> 75835 flows down to 43811 because tcprewrite seems to be giving
> different IP address's the same IP which put's some of the connections
in the same tuple.
>
> I picked out what should be 2 small flows for an example of what is
> happening throughout the rewrite multiple times.  Looking at packet 4,
> you can see that rewrite has given the packet the same IP as the first
> 3 packets.  Is there a reason this is happening?  I tried using the
> same command on the original_sample.pcap and the rewrite worked
> perfectly.  So the problem only exists when the file is 2.5 GB.
>
>
>
> My original_sample.pcap:
> 1   0.000000  103.0.2.140 -> 103.0.6.140  TCP edtools > http [SYN] Seq=0
> Win=2048 Len=0 WS=9
>
>   2   0.005000  103.0.6.140 -> 103.0.2.140  TCP http > edtools [SYN,
ACK]
> Seq=0 Ack=1 Win=2048 Len=0 WS=9
>
>   3   0.023000  103.0.2.140 -> 103.0.6.140  TCP edtools > http [ACK]
Seq=1
> Ack=1 Win=1048576 Len=0
>
>   4   0.174000  103.0.2.143 -> 103.0.6.143  TCP edtools > http [SYN]
Seq=0
> Win=2048 Len=0 WS=9
>
>   5   0.179000  103.0.6.143 -> 103.0.2.143  TCP http > edtools [SYN,
ACK]
> Seq=0 Ack=1 Win=2048 Len=0 WS=9
>
>   6   0.208000  103.0.2.143 -> 103.0.6.143  TCP edtools > http [ACK]
Seq=1
> Ack=1 Win=1048576 Len=0
>
>   7   0.403000  103.0.2.140 -> 103.0.6.140  HTTP GET
> /services/auth/?api_key=610346c7619bc6bd51afbbd2739f8d1f&api_sig=b993d
> e5486706c18a08757948c04963e&perms=write&frob=72157627531937949-7b4cf50
> cc91b7232-326096
> HTTP/1.1
>
>   8   0.475000  103.0.6.140 -> 103.0.2.140  TCP http > edtools [ACK]
Seq=1
> Ack=500 Win=1048576 Len=0
>
>   9   0.522000  103.0.2.143 -> 103.0.6.143  HTTP GET
> /services/auth/?api_key=610346c7619bc6bd51afbbd2739f8d1f&api_sig=b993d
> e5486706c18a08757948c04963e&perms=write&frob=72157627531937949-7b4cf50
> cc91b7232-326096
> HTTP/1.1
>
> 10   0.528000  103.0.6.143 -> 103.0.2.143  TCP http > edtools [ACK]
Seq=1
> Ack=500 Win=1048576 Len=0
>
>
>
> The rewrite_sample:
> 1   0.000000 39.66.178.173 -> 39.66.182.173 TCP edtools > http [SYN]
Seq=0
> Win=2048 Len=0 WS=9
>
>   2   0.005000 39.66.182.173 -> 39.66.178.173 TCP http > edtools [SYN,
ACK]
> Seq=0 Ack=1 Win=2048 Len=0 WS=9
>
>   3   0.023000 39.66.178.173 -> 39.66.182.173 TCP edtools > http [ACK]
Seq=1
> Ack=1 Win=1048576 Len=0
>
>   4   0.174000 39.66.178.173 -> 39.66.182.173 TCP [TCP Port numbers
reused]
> edtools > http [SYN] Seq=0 Win=2048 Len=0 WS=9
>
>   5   0.179000 39.66.182.173 -> 39.66.178.173 TCP http > edtools [SYN,
ACK]
> Seq=0 Ack=1 Win=2048 Len=0 WS=9
>
>   6   0.208000 39.66.178.173 -> 39.66.182.173 TCP edtools > http [ACK]
Seq=1
> Ack=1 Win=1048576 Len=0
>
>   7   0.403000 39.66.178.173 -> 39.66.182.173 HTTP [TCP ACKed lost
segment]
> [TCP Retransmission] GET
> /services/auth/?api_key=610346c7619bc6bd51afbbd2739f8d1f&api_sig=b993d
> e5486706c18a08757948c04963e&perms=write&frob=72157627531937949-7b4cf50
> cc91b7232-326096
> HTTP/1.1
>
>   8   0.475000 39.66.182.173 -> 39.66.178.173 TCP http > edtools [ACK]
> Seq=285549713 Ack=2574765636 Win=1048576 Len=0
>
>   9   0.522000 39.66.178.173 -> 39.66.182.173 HTTP GET
> /services/auth/?api_key=610346c7619bc6bd51afbbd2739f8d1f&api_sig=b993d
> e5486706c18a08757948c04963e&perms=write&frob=72157627531937949-7b4cf50
> cc91b7232-326096
> HTTP/1.1
>
> 10   0.528000 39.66.182.173 -> 39.66.178.173 TCP http > edtools [ACK]
Seq=1
> Ack=500 Win=1048576 Len=0
>
>
>
> Thanks,
>
> Eric
>
>
>
>
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--
Aaron Turner
http://synfin.net/         Twitter: @synfinatic
http://tcpreplay.synfin.net/ - Pcap editing and replay tools for Unix &
Windows Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety.
    -- Benjamin Franklin
"carpe diem quam minimum credula postero"

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Exclusive live event will cover all the ways today's security and threat
landscape has changed and how IT managers can respond. Discussions will
include endpoint security, mobile security and the latest in malware
threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
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Support Information: http://tcpreplay.synfin.net/trac/wiki/Support

Re: [Tcpreplay-users] tcprewrite seed issues

edit and replay captured network traffic

Re: [Tcpreplay-users] tcprewrite seed issues