John

john

john is advanced password cracking tool which can be used to crack both Windows and Linux passwords. For learning use of john to crack windows passwords visit bkhive, samdump2, john and to learn use of john to crack Linux passwords visit unshadow, john.

On some Cent-OS distributions default installation of john using yum may give following error:

fopen: $JOHN/dumb16.conf: No such file or directory

which can be resolved by installing john from source. Latest john source can be obtained from http://www.openwall.com/john/

To install john from source use following steps:

1. extract john source code
2. Go to folder 'src'.
3. Compile john using makefile. For compiling john for x86-64 linux distributions one can use command:

   make linux-x86-64

   For other distributions use simple 'make' command without any argument to see full list of supported distributions.

4. Use 'which john' to find out location of existing john binary
5. If john binary installed via yum is located with help of 'which john' then replace that file with compiled john from run folder of extracted john source tree. If not copy 'run/john' binary to '/usr/bin' folder.
6. IMP- Copy john.conf file from 'run' folder to '/etc' and also to folder where john executable is copied. This file must be present in working directory when using john. Hence to use john from '/root', one would have to copy 'john.conf' from one of these locations to '/root' before one can use john there. Error shown in absence of 'john.conf' file in current folder is:

   fopen: john.ini: No such file or directory