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Date: Mon, 31 Dec 2012 23:13:02 +0000
From: John Hall <JohnH@...tworking.com>
To: "'john-users@...ts.openwall.com'" <john-users@...ts.openwall.com>
Subject: john and muti-core settings and progress display
When using john with the jumbo patch and enabling multi-core on a Fedora 17 OS on vmWare VMworkstation with 2 cores enabled per below, I noticed that pressing "any key" when john is grinding away produces a different progress display that I saw with single core.
With single core I saw something like "...trying: Initialguessabc123"
With multicore I saw something like "...trying Initialguessabc123 - Initialguessxyz456"
So is john actually running 2 threads and each separately is attempting to discover the hash code? If so, presume that somehow there is no duplication of effort.
Could someone please comment on how to interpret the two passwords being tried and how the multi-core (or multi-cpu) system works.
John H.
-----Original Message-----
From: Solar Designer [mailto:solar@...nwall.com]
Sent: Saturday, December 29, 2012 10:53 AM
To: john-users@...ts.openwall.com
Subject: Re: [john-users] pwsafe2john - How to use this program, preferably in Windows or in Linux if Windows is a no-go?
On Sat, Dec 29, 2012 at 07:17:50AM +0000, John Hall wrote:
> 1. installed Fedora 17 Desktop on VM Workstation running on Win 7, 64-bit.
FWIW, you could as well install Cygwin (32-bit) on your Windows, and then make and run a JtR unstable-jumbo build for Win32, without a VM.
The approach with a VM is also fine, though.
> 7. make clean linux-x86-sse2
To use more than one CPU core, you may want to enable OpenMP support in the Makefile by uncommenting this line:
#OMPFLAGS = -fopenmp -msse2
(remove the "#" character). Dhiru's pwsafe format in JtR supports that.
However, please note that your VM settings (if you continue to use a VM) will need to be such that multiple logical CPUs are seen from the VM.
(The default is often to provide only one logical CPU to the VM.)
If you choose to use Cygwin instead, there's another potential hurdle - because of a Cygwin issue, you may need to take the cygwin1.dll file from our official builds of (older versions of) JtR for Win32 (e.g., from john179w2.zip linked from the JtR homepage). This issue is specific to Cygwin and OpenMP, and it manifests itself in JtR stopping to respond to keypresses (and not making any progress with the cracking
either) after it's been running for a little while (e.g. a few minutes).
The cygwin1.dll file in our .zip's has a workaround for this.
Alexander
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