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Date: Sat, 14 Jan 2012 10:47:09 +0400
From: Solar Designer <>
Subject: Re: john.pot problem

On Fri, Jan 13, 2012 at 04:02:44PM -0500, David LaPorte wrote:
> Apologies if this is just user error, but I'm having a strange problem
> that I haven't run into in the past.

Thank you for reporting this!

Lukas - can you try to reproduce and fix it, please?

> I'm executing JtR 1.79 patched
> with john-1.7.9-allopencl-04.diff in the background with the following:
> ./john --rules --format=cryptmd5opencl --wordlist=<path to my dict>
> /home/dlaporte/hashes &

BTW, for slow hash types like this, you may want to eliminate duplicate
candidate passwords resulting from the application of rules.  So you'd
use something like this:

./john --wordlist=<path to my dict> --rules --stdout | ./unique mangled.lst
./john --wordlist=mangled.lst --format=cryptmd5opencl /home/dlaporte/hashes

> John runs overnight and cracks 2 hashes:
> [dlaporte@...ry run]$ tail -2 john.log
> 0:10:11:11 + Cracked user4
> 0:16:26:36 + Cracked user7
> [dlaporte@...ry run]$ ./john --status
> guesses: 2  time: 0:23:32:05 7%  c/s: 46499

BTW, the c/s rate is quite low for OpenCL.  What hardware, OS, OpenCL
implementation is that?

For example, you can obtain a c/s rate like this (for the same hash type
indeed) on a Core 2 Duo by building -jumbo with the linux-x86-64i make
target and enabling OpenMP in the Makefile - that's without OpenCL.

> However, the pot is empty:
> [dlaporte@...ry run]$ ls -al john.pot
> -rw-------. 1 dlaporte dlaporte 0 Jan 12 09:13 john.pot
> I've sent a SIGHUP which updates the "--status" data, but the pot still
> remains empty:
> [dlaporte@...ry run]$ kill -HUP 3698 # john's PID
> [dlaporte@...ry run]$ ./john --status
> guesses: 2  time: 0:23:33:12 7%  c/s: 46497

This does indeed look like a bug, but I'm not sure where the bug is.

> Am I missing something obvious here?

No, I think you are not.

Thanks again,


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