john-users - Questions and suggestions to build a home cracking box. :)

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Message-ID: <CAFMma9ODiyzdrmdyySEePKViukP1Rq5y+ZLt+40rjd4F6PhobA@mail.gmail.com>
Date: Tue, 19 Nov 2013 23:47:47 -0600
From: Richard Miles <richard.k.miles@...glemail.com>
To: john-users@...ts.openwall.com
Subject: Questions and suggestions to build a home cracking box. :)

Good night,

I saved some money and I decided to build / buy a home-made box dedicated
for cracking. I will give a few details about what I expect and also some
questions and I will be very thankful for all answers, in special for
individuals with experience on the field. :)

I will be using exclusively John The Ripper tool, no other tools such as
hashcat. I will be running Linux (32 or 64 bits?).

Let me ask some basic questions before go deeper:

1) Modern processors contains multiple cores and threads (there are some
good processors with 4 cores and 2 threads per core = 8 cores). Most of my
cracking tasks will be exclusively against one single password hash,
consequently use --fork or spawn multiple process will be useless, correct?

2) Is there a reliable way to use jTr with multiple cores and threads at
the same time to try crack one single password hash? How?

3) Most of the references that I found about benchmark and GPUs are
outdates or used other tools, for example:

http://hashcat.net/oclhashcat-plus/

http://blog.erratasec.com/2011/06/password-cracking-mining-and-gpus.html#.UoxBtqlNNcQ

a) They clearly state that Radeon cards are much faster. My question is,
this information is still true recently?

b) I have heard that Radeons drivers sucks and are very unstable. Is that
true?

c) What is JtR actual support for Radeon cards? At the moment and further
efforts are better Radeon or Nvidia?

d) The infamous Radeon 6990 is not produced anymore and the used ones are
more expensive in comparison with 7970. LOL! There are newer models that
was unavailable at that time. What do you guys suggest? Should I buy 2
better GPUs? Or 3 GPUs that are average? Or one single super GPU?

e) Is is possible to do overclock on processors and GPU cards under Linux?
Is it recommended? What tools are available?

f) Finally, based on your suggestion of GPU card, what are the current
password hash formats supported?

4) Once using GPU for cracking with jTr is it possible to use with
incremental mode?

5) Once using GPU for cracking with jTr is it possible to use with markov
mode?

6) Suppose that I have a wordlist of almost 70GB. In this case the memory
of motherboard and memory of graphical card will influence a lot or not?

7) Does it worth to use two GPU cards together? Should they be connected
via crossfire? Or not? Is there any specific advantage for password
cracking with jTr?

8) Finally, I'm very concerned about power supply and cooler. What do you
guys recommend for a safe setup to keep this box running for week without
temperature issues? :)

a) Should I consider a watercooler for my processor?

b) Should I consider a special cooler for GPU card?

I was thinking about the following potential configurations:

Processor:         Core i7 (4770) - 3.40GHz Quad Box (intel)

Motherboard:    GA-H81M-S2PV (Gigabyte)

Memory:             8GB DDR3 1600MHz Corsair (2 units) = 16GB

HD:                     1TB 7200RPM (Sata 3.0) - to be used with really big
wordlists and other toys.

SSD:                   128GB Corsair (for Linux operating system)

GPU:        Radeon HD 7970 3GB GDDR5 384-bit (AMD) (2 units)

DVD:      LG read and write

Power Supply:   800W | GS800 V2 (Corsair)

Cabinet:              K380 (Collermaster)





Processor:         AM3+ TDP 125W - Piledriver FX8350 4.0GHz Octa-Core (AMD)

Motherboard:    GA-970A-DS3P (Gigabyte)

Memory:             8GB DDR3 1600MHz Corsair (2 units) = 16GB

HD:                     1TB 7200RPM (Sata 3.0) - to be used with really big
wordlists and other toys.

SSD:                   128GB Corsair (for Linux operating system)

GPU:        Radeon HD 7870 2GB GDDR5 256-bit (AMD) (3 units)

DVD:      LG read and write

Power Supply:  800W | GS800 V2 (Corsair)

Cabinet:            Thermaltake Armor Revo Gene Black

Suggestions and modifications are very welcome, but please, write the
reason and keep in mind price / benefit :)

Thanks a lot.
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