# Package metadata for krb5-strength.
#
# This file contains configuration for DocKnot used to generate
# documentation files (like README.md) and web pages. Other documentation
# in this package is generated automatically from these files as part of
# the release process. For more information, see DocKnot's documentation.
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# DocKnot is available from .
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# Copyright 2007, 2009-2010, 2012-2014, 2016-2017, 2020, 2023
# Russ Allbery
#
# SPDX-License-Identifier: MIT
format: v1
name: krb5-strength
maintainer: Russ Allbery
version: '3.3'
synopsis: Kerberos password strength checking plugin
license:
name: Expat
notices: |
Developed by Daria Phoebe Brashear and Ken Hornstein of Sine Nomine
Associates, on behalf of Stanford University.
The embedded version of CrackLib (all files in the `cracklib`
subdirectory) is covered by the Artistic license. See the file
`cracklib/LICENCE` for more information. Combined derivative works that
include this code, such as binaries built with the embedded CrackLib, will
need to follow the terms of the Artistic license as well as the above
license.
copyrights:
- holder: Russ Allbery
years: 2016, 2020, 2023
- holder: The Board of Trustees of the Leland Stanford Junior University
years: 2006-2007, 2009-2010, 2012-2014
- holder: Alec Muffett
years: '1993'
build:
autoconf: '2.64'
automake: '1.11'
autotools: true
kerberos: true
manpages: true
reduced_depends: true
bootstrap: |
You will also need Perl 5.010 or later and the Const::Fast, DBI,
DBD::SQLite, JSON::MaybeXS, and Perl6::Slurp modules (from CPAN) to
bootstrap the test suite data from a Git checkout.
middle: |
By default, the Heimdal external password check function is installed as
`/usr/local/bin/heimdal-strength`, and the plugin is installed as
`/usr/local/lib/krb5/plugins/pwqual/strength.so`. You can change these
paths with the `--prefix`, `--libdir`, and `--bindir` options to
`configure`.
By default, the embedded version of CrackLib will be used. To build with
the system version of CrackLib, pass `--with-cracklib` to `configure`.
You can optionally add a directory, giving the root directory where
CrackLib was installed, or separately set the include and library path
with `--with-cracklib-include` and `--with-cracklib-lib`. You can also
build without any CrackLib support by passing `--without-cracklib` to
`configure`.
krb5-strength will automatically build with TinyCDB if it is found. To
specify the installation path of TinyCDB, use `--with-tinycdb`. You can
also separately set the include and library path with
`--with-tinycdb-include` and `--with-tinycdb-lib`.
Similarly, krb5-strength will automatically build with SQLite if it is
found. To specify the installation path of SQLite, use `--with-sqlite`.
You can also separately set the include and library path with
`--with-sqlite-include` and `--with-sqlite-lib`.
suffix: |
After installing this software, see the man pages for krb5-strength,
heimdal-strength, and heimdal-history for configuration information.
type: Autoconf
valgrind: true
distribution:
section: kerberos
tarname: krb5-strength
version: krb5-strength
packaging:
debian:
package: krb5-strength
summary: |
A Debian package is included in Debian 8.0 (jessie) and later
releases.
support:
email: eagle@eyrie.org
github: rra/krb5-strength
web: https://www.eyrie.org/~eagle/software/krb5-strength/
vcs:
browse: https://git.eyrie.org/?p=kerberos/krb5-strength.git
github: rra/krb5-strength
openhub: https://www.openhub.net/p/krb5-strength
status:
workflow: build
type: Git
url: https://git.eyrie.org/git/kerberos/krb5-strength.git
docs:
user:
- name: heimdal-history
title: heimdal-history
- name: heimdal-strength
title: heimdal-strength
- name: krb5-strength
title: krb5-strength plugin
- name: wordlist
title: krb5-strength-wordlist
developer:
- name: todo
title: To-do list
blurb: |
krb5-strength provides a password quality plugin for the MIT Kerberos KDC
(specifically the kadmind server) and Heimdal KDC, an external password
quality program for use with Heimdal, and a per-principal password history
implementation for Heimdal. Passwords can be tested with CrackLib,
checked against a CDB or SQLite database of known weak passwords with some
transformations, checked for length, checked for non-printable or
non-ASCII characters that may be difficult to enter reproducibly, required
to contain particular character classes, or any combination of these
tests.
description: |
Heimdal includes a capability to plug in external password quality checks
and comes with an example that checks passwords against CrackLib.
However, in testing at Stanford, we found that CrackLib with its default
transform rules does not catch passwords that can be guessed using the
same dictionary with other tools, such as Jack the Ripper. We then
discovered other issues with CrackLib with longer passwords, such as some
bad assumptions about how certain measures of complexity will scale, and
wanted to impose other limitations that it didn't support.
This plugin provides the ability to check password quality against the
standard version of CrackLib, or against a modified version of CrackLib
that only passes passwords that resist attacks from both Crack and Jack
the Ripper using the same rule sets. It also supports doing simpler
dictionary checks against a CDB database, which is fast with very large
dictionaries, or a SQLite database, which can reject all passwords within
edit distance one of a dictionary word. It can also impose other
programmatic checks on passwords such as character class requirements.
If you're just now starting with password checking, I recommend using the
SQLite database with a large wordlist and minimum password lengths. We
found this produced the best results with the least user frustration.
For Heimdal, krb5-strength includes both a program usable as an external
password quality check and a plugin that implements the dynamic module
API. For MIT Kerberos (1.9 or later), it includes a plugin for the
password quality (pwqual) plugin API.
krb5-strength can be built with either the system CrackLib or with the
modified version of CrackLib included in this package. Note, however,
that if you're building against the system CrackLib, Heimdal includes in
the distribution a strength-checking plugin and an external password check
program that use the system CrackLib. With Heimdal, it would probably be
easier to use that plugin or program than build this package unless you
want the modified CrackLib, one of the other dictionary types, or the
additional character class and length checks.
For information about the changes to the CrackLib included in this
toolkit, see `cracklib/HISTORY`. The primary changes are tighter rules,
which are more aggressive at finding dictionary words with characters
appended and prepended, which tighten the requirements for password
entropy, and which add stricter rules for longer passwords. They are also
minor changes to fix portability issues, remove some code that doesn't
make sense in the kadmind context, and close a few security issues. The
standard CrackLib distribution on at least some Linux distributions now
supports an additional interface to configure its behavior, and
krb5-strength should change in the future to use that interface and drop
the embedded copy.
krb5-strength also includes a password history implementation for Heimdal.
This is separate from the password strength implementation but can be
stacked with it so that both strength and history checks are performed.
This history implementation is available only via the Heimdal external
password quality interface. MIT Kerberos includes its own password
history implementation.
requirements: |
For Heimdal, you may use either the external password quality check tool,
installed as heimdal-strength, or the plugin as you choose. It has been
tested with Heimdal 1.2.1 and later, but has not recently been tested with
versions prior to 7.0.
For MIT Kerberos, version 1.9 or higher is required for the password
quality plugin interface. MIT Kerberos does not support an external
password quality check tool directly, so you will need to install the
plugin.
You can optionally build against the system CrackLib library. Any version
should be supported, but note that some versions, particularly older
versions close to the original code, do things like printing diagnostics
to stderr, calling exit, and otherwise not being well-behaved for use
inside plugins or libraries. They also have known security
vulnerabilities. If using a system CrackLib library, use version 2.8.22
or later to avoid these problems.
You can also optionally build against the TinyCDB library, which provides
support for simpler and faster password checking against a CDB dictionary
file, and the SQLite library (a version new enough to support the
`sqlite3_open_v2` API; 3.7 should be more than sufficient), which provides
support for checking whether passwords are within edit distance one of a
dictionary word.
For this module to be effective for either Heimdal or MIT Kerberos, you
will also need to construct a dictionary. The `mkdict` and `packer`
utilities to build a CrackLib dictionary from a word list are included in
this toolkit but not installed by default. You can run them out of the
`cracklib` directory after building. You can also use the utilities that
come with the stock CrackLib package (often already packaged in a Linux
distribution); the database format is compatible.
For building a CDB or SQLite dictionary, use the provided
`krb5-strength-wordlist` program. For CDB dictionries, the `cdb` utility
must be on your `PATH`. For SQLite, the DBI and DBD::SQLite Perl modules
are required. `krb5-strength-wordlist` requires Perl 5.010 or later.
For a word list to use as source for the dictionary, you can use
`/usr/share/dict/words` if it's available on your system, but it would be
better to find a more comprehensive word list. Since word lists are
bulky, often covered by murky copyrights, and easily locatable on the
Internet with a modicum of searching, none are included in this toolkit.
The password history program, heimdal-history, requires Perl 5.010 or
later plus the following CPAN modules:
* Const::Fast
* Crypt::PBKDF2
* DB_File::Lock
* Getopt::Long::Descriptive
* IPC::Run
* JSON::MaybeXS
and their dependencies.
test:
lancaster: true
suffix: |
To run the test suite, you will need Perl 5.010 or later and the
dependencies of the `heimdal-history` program. The following additional
Perl modules will also be used by the test suite if present:
* Perl6::Slurp
* Test::MinimumVersion
* Test::Perl::Critic
* Test::Pod
* Test::Spelling
* Test::Strict
All are available on CPAN. Some tests will be skipped if the modules
are not available.