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Date: Fri, 29 Jan 2016 22:47:23 -0500
From: japhar81 <>
Subject: Re: MPI with Spot Instances?

I'm still a bit fuzzy on the modes.. I'm going after a RAR file's hash (via
rar2john) in incremental mode.. which of those cases does that fall into?

On Fri, Jan 29, 2016 at 10:44 PM, magnum <> wrote:

> On 2016-01-30 04:25, japhar81 wrote:
>> They basically just disappear, whatever they were in the middle of -- i
>> guess my question is, will the resume re-run whatever jobs those nodes
>> were
>> in the middle of and didn't report back? And if one of them happens to
>> have
>> hit a match, will that get saved somehow too?
> A cracked password is very unlikely to not end up in the pot file. The
> beauty of Solar's design is that if a session dies before it wrote a
> recently cracked password to the pot file, it will also not have written
> the corresponding unit of work to the session file. So a resume will almost
> certainly re-crack the password.
> Jumbo's MPI functionality is very KISS minded and doesn't rely on
> "reporting back" anything to anyone at all. Each node runs in its own daft
> world not giving a dang about the others. Each node writes its own session
> file just as any non-MPI session would. In fact, the code paths are *very*
> near 100% the same as when running --node=x/y in a single process except
> the "x" and "y" is filled in automagically.
> Worst-case scenario is supposedly that a resume will do a bit of redundant
> work. This is obviously by design - better safe than sorry. The default
> "Save" timer in john.conf is 60 seconds for Jumbo so you will hopefully not
> lose more than that. Some modes (eg. single w/ many salts and PRINCE
> regardless of salts) may be much worse than that though, to the point that
> a stop/resume once an hour may end up never proceeding past this hour at
> all.
> magnum
> On Fri, Jan 29, 2016 at 10:20 PM, magnum <> wrote:
>> On 2016-01-29 18:12, japhar81 wrote:
>>> Ok, so corollary question -- does the session stuff work with MPI? i.e.
>>>> lets say I start the spot instances externally, and mpiexec jtr with
>>>> some
>>>> flavor of --session (on a box that wont die). If those nodes die
>>>> mid-process, will that be recorded in the session to enable a resume
>>>> later
>>>> when I spin new nodes and start mpiexec again?
>>> Sure (as far as I can imagine how spot instances work). Session file
>>> integrity is very well tested.
>>> magnum
>>> On Wed, Jan 27, 2016 at 4:03 PM, magnum <>
>>> wrote:
>>>> On 2016-01-27 17:25, japhar81 wrote:
>>>>> I've been playing around with MPI clustering JtR for a while, and I've
>>>>>> managed to get it running smoothly on static nodes. What I'd like to
>>>>>> do
>>>>>> next is create an auto-scaling group in AWS, using spot instances.
>>>>>> What
>>>>>> this basically means is nodes will come and go, with their
>>>>>> hostnames/IPs
>>>>>> changing at random.. I can not figure out how I would run JtR in that
>>>>>> instance -- since it requires a node list in a file on startup to
>>>>>> mpirun.
>>>>>> If it matters, I'm looking to do a brute-force using the ASCII mode.
>>>>>> Has
>>>>>> anyone found a way to do a dynamic cluster that adds/removes nodes at
>>>>>> random? Is this even possible?
>>>>>> I'm not aware of any existing work that would do this. A solution
>>>>> using
>>>>> JtR as-is, but with some yet-to-be-implemented master issuing jobs,
>>>>> could
>>>>> involve looking at the existing "-node=x/y" as describing "pieces"
>>>>> instead
>>>>> of "nodes". So instead of saying -node=2/8 as in "you are node 2 of 8"
>>>>> you'd say -node=4321/100000 as in "do piece 4321 of 100000". Then you'd
>>>>> submit pieces to active nodes. Obviously you'd have to handle dying
>>>>> nodes
>>>>> that never reported back their given piece, and re-issue those pieces.
>>>>> magnum

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