Customizing John the Ripper.
John the Ripper's behavior can be customized by editing its
configuration file. The configuration file can be named either
john.conf (on Unix-like systems) or john.ini (on systems which have a
notion of filename "extensions" and limit them to 3 characters).
This file is searched for in private John's "home directory" and, if
not found in the private directory and John is installed system-wide,
also in John's system-wide shared data files directory.
You can set global options, define wordlist and "single crack" mode
rules, define parameters for "incremental" modes, or even define a new
external cracking mode.
The configuration file consists of several sections. Each section
starts with a line containing its name, in brackets ("[...]"). Sections
consist either of "variable = value" assignments (each on its own line)
or of some other content specific to the particular section's type
(names of such sections start with "List."). Section and variable names
are not case sensitive. Comment lines start with a hash character ("#")
or a semicolon (";") and are ignored. Also ignored are any empty lines.
General options.
Some global options can be defined in the [Options] section. Currently,
you can set the following options:
Wordlist = FILENAME
Set this to your wordlist file name, to be used in batch mode (which is
activated when you start John with password files, but not specifying a
cracking mode). The default is "$JOHN/password.lst", that is, the file
named "password.lst" in John's "home directory".
Idle = Y|N
If set to "Y" (yes), John will try to use idle processor cycles only,
thereby greatly reducing its impact on other system processes. The
impact on performance of John itself is negligible except on otherwise
overloaded systems. This setting does not affect John's startup time
and non-cracking invocations of John; it only affects the actual
cracking. The default is "Y" (yes).
Starting with version 1.7.7, this setting is ignored for OpenMP-enabled
hash types when the actual number of threads is greater than 1.
Unfortunately, it did not work right at least with GNU libgomp on Linux.
Save = SECONDS
This is the time interval (in seconds) between crash recovery file
updates. The default is 600 seconds (10 minutes).
Beep = Y|N
If set to "Y" (yes), John will beep when a password is found. On
Unix-like systems, it does this by sending the bell character (ASCII
code 7) to the "standard error" file descriptor (which is normally
directed to the terminal). The default is "N" (no).
Defining wordlist and "single crack" modes rules.
The word mangling rules for wordlist and "single crack" modes are
defined in separate sections, [List.Rules:Wordlist] and
[List.Rules:Single], respectively. John the Ripper uses an extension of
Crack's syntax for the rules. John supports all of the commands of
Crack 5.0a plus a few more and, most importantly, it adds a
preprocessor, which can generate multiple rules from a single source
line.
When defining rules, simply place one rule (which may include
preprocessor commands) per line. See RULES for information on the rules
syntax and on the preprocessor.
"Incremental" mode parameters.
To define the incremental mode parameters you need to create a section
called [Incremental:MODE], where MODE is any name that you assign to the
mode. There are some pre-defined incremental modes in the default
configuration file supplied with John, you can use them as templates.
The following parameters are supported:
File = FILENAME
Set this to your charset file name. See EXAMPLES for an example on how
to generate a custom charset file. There's no default.
MinLen = LENGTH
Minimum password length (the number of characters) to try. The default
is 0.
MaxLen = LENGTH
Maximum password length to try. The default is 8 (or CHARSET_LENGTH as
defined in src/params.h at compile time).
CharCount = COUNT
This allows you to limit the number of different characters (or rather,
character indices) used. The effect is that John would favor simple
longer candidate passwords over more complicated shorter ones, and would
never attempt rare characters and character combinations, not even for
really short passwords. Most of the time, this is undesired. Another
use for this option is to make John print a warning if the charset only
defines less than CharCount characters; this is how the pre-defined
"incremental" modes use it. The default is to use as many different
characters as are defined.
Extra = CHARACTERS
This can be used to make John try some extra characters that don't
appear in the charset file. Just list all those characters here and
they will be added, but considered the least probable.
Defining an external mode.
See EXTERNAL.
$Owl: Owl/packages/john/john/doc/CONFIG,v 1.5 2011/02/27 07:16:16 solar Exp $
