Re: Testing IDS with tcpreplay

["Aaron Turner" <synfinatic () gmail com>]

Hey Greg,

I think you make some good points.  If I could dare to offer to
summarize your argument against replay tools it would be "garbage in,
garbage out".  And it's something I'd have to agree with 100%.  If
you're not willing to take the time to make sure your captures contain
the "correct" information (however that might be defined) then you're
asking for trouble.  It's one of the reasons why I haven't tried
making pcaps available for public consumption.

I hope nobody thinks tcpreplay/tomahawk/IDS Informer/TrafficIQ are the
best solution for the entire IDS/IPS testing space, because they're
clearly not.  There are some areas (like regression) where it tends to
work well (at least certain vendors have told me so) and others where
it falls flat.  It may not be 100% accurate, but doing valid tests 90%
of the time is better then no tests 100% of the time.

IMHO, the difference between "actual attacks" and "specific sequence
of packets" is that you haven't verified that your sequence of packets
is the correct representation of the actual attack.  In a controlled
lab environment, it's not hard, but it takes effort and people like
shortcuts.  (Note to those still reading: If you're not including that
shell, reverse socket or whatever in your pcap showing the attack was
sucessful, you're leaving out important information.)

Luckly for everyone there are plenty of free and commercial tools out
there to fill your toolbox with.  I encourage everyone to do their
homework and figure out how to base-line their tools... after all
these tools contain code developed by humans and probably have as many
bugs as the devices they're testing.  If you ever look at the
tcpreplay changelog you'll know what I'm talking about. :)

And now to summarize my email: YMMV.

Regards,
Aaron

--
Aaron Turner
http://synfin.net/

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