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--- use_john_the_ripper_to_crack_password_hashes [31.01.2021 03:05] – Pascal Suter
+++ use_john_the_ripper_to_crack_password_hashes [31.01.2021 22:11] – [compile with OpenCL support to run on NVIDIA (and other) GPU's (tested on CentOS)] Pascal Suter
@@ Line 53: / Line 53: @@
 the ''-dev=gpu -fork=8'' options are there to use all cards in parallel. this will fork 8 individual processes each working on their own range of passwords at a time and each on a different GPU. If you have multiple hosts with GPU you may use MPI for that.
+===== continue an interrupted session =====
+John saves its status as it's working, so in case it crashes or you have to abort it because you need to work with your pc and don't want the cpu load on it for example, you can always resume the session and continue where John has left off.
+BUT.. it is **important** that you specify the ''--restore'' option, otherwise john will start over again! To avoid accidently starting over and by doing so loosing all the previous compute time, it is advisable to give each session its own **session name** by using the ''--session:<name>'' parameter. By doing so, you can avoid overwriting the session in case you start another john session in the mean time.
+so you would start john like this:
+  john --session:sess1 unshadow.txt
+and then resume the session like so:
+  john --restore:sess1
+also the other commands like for example ''status'' accept a session name parameter:
+  john --status:sess1
+===== Performance examples =====
+if you press any key during the run, you will get a status showing you c/s (crypts per second). here are a few numbers from the systems i had access to at the moment of writing this article:
+^ CPU / GPU ^ c/s rate ^ method used ^
+| 8-core i7-8809G CPU| 7'500 | OpenMP |
+| 128-core (2 socket) AMD ROME 7742| 150'000 | OpenMP |
+| 8 x GeForce RTX 2080 Ti | 8x190'000 | Fork |