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Date: Mon, 21 Sep 2015 06:47:57 +0200
From: Frank Dittrich <>
Subject: Re: best setup to crack format nt or nt2

On 09/20/2015 10:35 PM, Patrick Proniewski wrote:
> Hello,
> I plan to make some kind of password audit at work. The purpose is to warn users about weak password, when they use one.
> I'm going to dump Active Directory accounts (2008 R2), convert to some kind of GECOS format and launch John on the resulting file.

Most likely, you will crack many hashes.
But I would blame the poor password hash algorithm (fast, and even
worse: not salted) at least as much as the user's choice of poor passwords.
It has been known for many years that this hash algorithm is crap.

> I would like to run John for 24 hours on a decommissioned blade server, so I got 8 cpu cores, and lots of RAM, no GPU at all. What would be the best way to use most of this hardware? If I'm not mistaken, nt/nt2 can't get OpenMP benefits, so I could have to split the password file into 8 chunks, or use fork, or any other parallelism setup.

Don't split the passwords.
Since the hashes are not salted, you would waste a lot of time.
(Comparing a computed hash against a salt is much faster than computing
a hash.)
Use --fork, and/or run different attacks against all the hashes on your
different cores.


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