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When invoked with no command line arguments, "john" prints its usage summary.
The supported command line arguments are password file names and options. Many of the supported options accept additional arguments.
You can list any number of password files right on the command line of "john". You do not have to specify any options. If valid password files are specified but no options are given, John will go through the default selection of cracking modes with their default settings.
Options may be specified along with password files or on their own, although some require that password files be specified and some do not support operation on password files.
All options are case sensitive, can be abbreviated as long as the abbreviations are unambiguous, can be prefixed with two dashes (GNU-style) or with one dash, and can use "=" or ":" to indicate an argument (if supported for a given option).
The supported options are as follows, square brackets denote optional arguments:
--single "single crack" mode
Enables the "single crack" mode, using rules from the configuration file section [List.Rules:Single].
--wordlist=FILE wordlist mode, read words from FILE, --stdin or from stdin
These are used to enable the wordlist mode.
--rules enable word mangling rules for wordlist mode
Enables word mangling rules that are read from [List.Rules:Wordlist].
--incremental[=MODE] "incremental" mode [using section MODE]
Enables the "incremental" mode, using the specified configuration file definition (section [Incremental:MODE], or [Incremental:All] by default except for LM hashes for which the default is [Incremental:LanMan]).
--external=MODE external mode or word filter
Enables an external mode, using external functions defined in section [List.External:MODE].
--stdout[=LENGTH] just output candidate passwords
When used with a cracking mode, except for "single crack", makes John output the candidate passwords it generates to stdout instead of actually trying them against password hashes; no password files may be specified when this option is used. If a LENGTH is given, John assumes that to be the significant password length and only produces passwords up to that length.
--restore[=NAME] restore an interrupted session
Continues an interrupted cracking session, reading state information from the specified session file or from $JOHN/john.rec by default.
--session=NAME give a new session the NAME
This option can only be used when starting a new cracking session and its purpose is to give the new session a name (to which John will append the ".rec" suffix to form the session file name). This is useful for running multiple instances of John in parallel or to be able to later recover a session other than the last one you interrupt.
--status[=NAME] print status of a session [called NAME]
Prints status of an interrupted or running session. Note that on a Unix-like system, you can get a detached running session to update its session file by sending a SIGHUP to the appropriate "john" process; then use this option to read in and display the status.
--make-charset=FILE make a charset, overwriting FILE
Generates a charset file based on character frequencies from $JOHN/john.pot, for use with "incremental" mode. The entire $JOHN/john.pot will be used for the charset generation unless you specify some password files in which case only the cracked passwords which correspond to those password files will be used. You can also use an external filter() routine with this option.
--show show cracked passwords
Shows the cracked passwords for given password files (which you must specify). You can use this option while another instance of John is cracking to see what John did so far; to get the most up to date information, first send a SIGHUP to the appropriate "john" process.
--test perform a benchmark
Benchmarks all of the compiled in hashing algorithms and tests them for proper operation.
--users=[-]LOGIN|UID[,..] [do not] load this (these) user(s)
Allows you to select just a few accounts for cracking or for other operations. A dash before the list can be used to invert the check (that is, load information for all the accounts that are not listed).
--groups=[-]GID[,..] load users [not] of this (these) group(s)
Tells John to load (or to not load) information for accounts in the specified group(s) only.
--shells=[-]SHELL[,..] load users with[out] this (these) shell(s)
This option is useful to load accounts with a valid shell only or to not load accounts with a bad shell. You can omit the path before a shell name, so "--shells=csh" will match both "/bin/csh" and "/usr/bin/csh", while "--shells=/bin/csh" will only match "/bin/csh".
--salts=[-]COUNT load salts with[out] at least COUNT passwords
This is a feature which allows to achieve better performance in some special cases. For example, you can crack only some salts using "--salts=2" faster and then crack the rest using "--salts=-2". Total cracking time will be about the same, but you will likely get some passwords cracked earlier.
--format=NAME force ciphertext format NAME
Allows you to override the hash type detection. Currently, valid "format names" are DES, BSDI, MD5, BF, AFS, and LM. You can use this option when cracking or with "--test". Note that John can't crack hashes of different types at the same time. If you happen to get a password file which uses more than one hash type (for different accounts), then you have to invoke John once for each hash type and you need to use this option to make John crack hashes of types other than the one it would autodetect by default.
--save-memory=LEVEL enable memory saving, at LEVEL 1..3
You might need this option if you don't have enough memory or don't want John to affect other processes too much. Level 1 tells John to not waste memory on login names; it is only supported when a cracking mode other than "single crack" is explicitly requested. The only impact is that you won't see the login names while cracking. Higher memory saving levels have a performance impact; you should probably avoid using them unless John doesn't work or gets into swap otherwise.
There are some related utilities in John's run directory:
unshadow PASSWORD-FILE SHADOW-FILE
Combines the "passwd" and "shadow" files (when you already have access to both) for use with John. You might need this since if you only used your shadow file, the "Full Name" or "GECOS" information wouldn't be used by the "single crack" mode (thus reducing its efficiency) and you wouldn't be able to use the "--groups" and "--shells" options and to select by UID with "--users". You probably also want to see all of the passwd file fields with "--show".
You'll usually want to redirect the output of "unshadow" to a file which you then pass to John.
unafs DATABASE-FILE CELL-NAME
Gets password hashes out of the binary AFS database and produces output usable by John (you should redirect the output to a file).
Removes duplicates from a wordlist (read from stdin) without changing the order of entries. You might want to use this with John's "--stdout" option if you've got a lot of disk space to trade for the reduced cracking time (on possibly trying some duplicates as they might be produced with word mangling rules).
A shell script to send mail to all the users who got weak passwords. You should edit the message inside the script before using it.
$Owl: Owl/packages/john/john/doc/OPTIONS,v 1.3 2005/11/16 13:11:15 solar Exp $