All rights reserved.
Copyright (c) 2001 Networks Associates Technology, Inc.
All rights reserved.
Portions of this software were developed for the FreeBSD Project by
ThinkSec AS and NAI Labs, the Security Research Division of Network
Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035
("CBOSS"), as part of the DARPA CHATS research program.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. The name of the author may not be used to endorse or promote
products derived from this software without specific prior written
permission.
THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
$FreeBSD: head/lib/libpam/modules/pam_passwdqc/pam_passwdqc.8 97607 2002-05-30 14:49:57Z ru $
.Dd April 15, 2002 .Dt PAM_PASSWDQC 8 .Os .Sh NAME .Nm pam_passwdqc .Nd Password quality-control PAM module .Sh SYNOPSIS .Op Ar service-name .Ar module-type .Ar control-flag
a pam_passwdqc .Op Ar options .Sh DESCRIPTION The .Nm module is a simple password strength checking module for PAM. In addition to checking regular passwords, it offers support for passphrases and can provide randomly generated passwords.
p The .Nm module provides functionality for only one PAM category: password changing. In terms of the .Ar module-type parameter, this is the .Dq Li password feature.
p The .Fn pam_chauthtok service function will ask the user for a new password, and verify that it meets certain minimum standards. If the chosen password is unsatisfactory, the service function returns .Dv PAM_AUTHTOK_ERR .
p The following options may be passed to the authentication module: l -tag -width indent t Xo .Sm off .Cm min No = Ar N0 , N1 , N2 , N3 , N4 .Sm on .Xc .Sm off
q Cm min No = Cm disabled , No 24 , 12 , 8 , 7 .Sm on The minimum allowed password lengths for different kinds of passwords/passphrases. The keyword .Cm disabled can be used to disallow passwords of a given kind regardless of their length. Each subsequent number is required to be no larger than the preceding one.
p .Ar N0 is used for passwords consisting of characters from one character class only. The character classes are: digits, lower-case letters, upper-case letters, and other characters. There is also a special class for .No non- Ns Tn ASCII characters which could not be classified, but are assumed to be non-digits.
p .Ar N1 is used for passwords consisting of characters from two character classes, which do not meet the requirements for a passphrase.
p .Ar N2 is used for passphrases. A passphrase must consist of sufficient words (see the .Cm passphrase option below).
p .Ar N3 and .Ar N4 are used for passwords consisting of characters from three and four character classes, respectively.
p When calculating the number of character classes, upper-case letters used as the first character and digits used as the last character of a password are not counted.
p In addition to being sufficiently long, passwords are required to contain enough different characters for the character classes and the minimum length they have been checked against.
p t Cm max Ns = Ns Ar N
q Cm max Ns = Ns 40 The maximum allowed password length. This can be used to prevent users from setting passwords which may be too long for some system services. The value 8 is treated specially: if .Cm max is set to 8, passwords longer than 8 characters will not be rejected, but will be truncated to 8 characters for the strength checks and the user will be warned. This is for compatibility with the traditional DES password hashes, which truncate the password at 8 characters.
p It is important that you do set .Cm max Ns = Ns 8 if you are using the traditional hashes, or some weak passwords will pass the checks. t Cm passphrase Ns = Ns Ar N
q Cm passphrase Ns = Ns 3 The number of words required for a passphrase, or 0 to disable passphrase support. t Cm match Ns = Ns Ar N
q Cm match Ns = Ns 4 The length of common substring required to conclude that a password is at least partially based on information found in a character string, or 0 to disable the substring search. Note that the password will not be rejected once a weak substring is found; it will instead be subjected to the usual strength requirements with the weak substring removed.
p The substring search is case-insensitive and is able to detect and remove a common substring spelled backwards. t Xo .Sm off .Cm similar No = Cm permit | deny .Sm on .Xc
q Cm similar Ns = Ns Cm deny Whether a new password is allowed to be similar to the old one. The passwords are considered to be similar when there is a sufficiently long common substring and the new password with the substring removed would be weak. t Xo .Sm off .Cm random No = Ar N Op , Cm only .Sm on .Xc
q Cm random Ns = Ns 42 The size of randomly-generated passwords in bits, or 0 to disable this feature. Passwords that contain the offered randomly-generated string will be allowed regardless of other possible restrictions.
p The .Cm only modifier can be used to disallow user-chosen passwords. t Xo .Sm off .Cm enforce No = Cm none | users | everyone .Sm on .Xc
q Cm enforce Ns = Ns Cm everyone The module can be configured to warn of weak passwords only, but not actually enforce strong passwords. The .Cm users setting will enforce strong passwords for non-root users only. t Cm non-unix Normally, .Nm uses .Xr getpwnam 3 to obtain the user's personal login information and use that during the password strength checks. This behavior can be disabled with the .Cm non-unix option. t Cm retry Ns = Ns Ar N
q Cm retry Ns = Ns 3 The number of times the module will ask for a new password if the user fails to provide a sufficiently strong password and enter it twice the first time. t Cm ask_oldauthtok Ns Op = Ns Cm update Ask for the old password as well. Normally, .Nm leaves this task for subsequent modules. With no argument, the .Cm ask_oldauthtok option will cause .Nm to ask for the old password during the preliminary check phase. If the .Cm ask_oldauthtok option is specified with the .Cm update argument, .Nm will do that during the update phase. t Cm check_oldauthtok This tells .Nm to validate the old password before giving a new password prompt. Normally, this task is left for subsequent modules.
p The primary use for this option is when .Cm ask_oldauthtok Ns = Ns Cm update is also specified, in which case no other modules gets a chance to ask for and validate the password. Of course, this will only work with x passwords. t Cm use_first_pass , use_authtok Use the new password obtained by modules stacked before .Nm . This disables user interaction within .Nm . The only difference between .Cm use_first_pass and .Cm use_authtok is that the former is incompatible with .Cm ask_oldauthtok . .El .Sh SEE ALSO .Xr getpwnam 3 , .Xr pam.conf 5 , .Xr pam 8 .Sh AUTHORS The .Nm module was written by .An Solar Designer Aq solar@openwall.com . This manual page, derived from the author's documentation, was written for the .Fx Project by ThinkSec AS and NAI Labs, the Security Research Division of Network Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035
q Dq CBOSS , as part of the DARPA CHATS research program.