Date: Fri, 4 Nov 2016 15:19:32 +0100 From: matlink <matlink@...link.fr> To: john-users@...ts.openwall.com Subject: Re: John does not fork as many times as I want Okay then there is less memory used when cracking hard password (allowing using more forks) than when freshly starting to crack the hashes? Is that linked to the "1/3" I can see on the john status? Step 3/3 requires less memory when forking than step 1/3? Le 04/11/2016 à 15:14, Solar Designer a écrit : > On Fri, Nov 04, 2016 at 02:59:10PM +0100, matlink wrote: >> I've omitted to tell something: >> >> after these missing forks, the main process returns me: >> >> 1:Fork: cannot allocate memory >> >> which explains why all forks are not poped. > Oh, sure. Sounds like you're cracking the full(er) LinkedIn dump than > was circulating in 2012, then, and your use of the "-linkedin" format is > inappropriate. Please use the simple "raw-SHA1" format instead. And > please use bleeding-jumbo. > >> However it seems that I >> still have plenty of available memory (about 200GB free). > You say you're requesting 40 forks, but only 5 processes are left. > This may mean that some of the other 35 were forked, fought for memory, > and then died - freeing up that 200 GB that you see. > >> Can this error come from another situation than lack of memory? > There are many other possibilities, but they are not likely in your case. > > The way "--fork" works, it does not multiply the memory needs of one > process by the number of processes right away. Most of the memory pages > are shared between the processes. However, when a lot of passwords get > cracked, the differences between the processes increase, and fewer pages > are shared. Thus, when cracking large password hash dumps like this, > you need to start with fewer forked processes to get the easiest > passwords cracked first, then after a few hours or days, when there are > relatively few hashes left to crack (e.g., 20% of original) and the > successful guesses are not as frequent, restart with your desired number > of processes. > > There were some changes in bleeding-jumbo (since 1.8.0-jumbo-1) that > should partially mitigate this issue, so maybe you'd be able to run more > processes with it now, but overall my suggested approach above is still > the way to go. > > Alexander -- Matlink - Sysadmin matlink.fr Sortez couverts, chiffrez vos mails : https://café-vie-privée.fr/ XMPP/Jabber : matlink@...link.fr Clé publique PGP : 0x186BB3CA Empreinte Off-the-record : 572174BF 6983EA74 91417CA7 705ED899 DE9D05B2
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