Re: [NSE] DB2 library and scripts

[Fyodor <fyodor () insecure org>]

On Tue, May 11, 2010 at 07:57:34PM +0200, Patrik Karlsson wrote:
> Hi again,
>
> I'm attaching yet another version of the DB2-brute script.
> In this version, I've used the excellent code provided by Patrick (thanks!) and changed the behavior/design according 
> to Fyodor's suggestions [1].
> I'm also providing some *very* simple benchmarking of this new script and the old single threaded one running against 
> DB2 on Linux.

Thanks Patrik.  And David had a great idea (which he already posted)
about running 10 non-parallelized scripts separately and seeing how
that compares.

> So this rudimentary benchmark suggests a 25% performance increase
> when running with 10 threads.  Increasing the threads to 20 by using
> the db2-brute.threads argument did not show any additional
> performance increase.

Perhaps the number of threads should be dynamic?  Maybe it should
start with one and try to increase the number by one (up to a
configured maximum) every X seconds.  Then it could crack another X
seconds and look at whether the rate increased or decreased in this
segment vs. the one before the increase.  If the rate increased, bump
up the threads again.  But if the rate stayed the same or decreased,
bump the thread count back down.

This is very similar to how Nmap's port scanning algorithm works.  It
is always trying to go faster, but then slows down if accuracy is
hurt.

Admittedly this is much more of a pain to implement, but the
performance gains may be worth it.

Cheers,
-F
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