How to display password policy information for a user (Ubuntu)?

Question

Ubuntu Documentation > Ubuntu 9.04 > Ubuntu Server Guide > Security > User Management states that there is a default minimum password length for Ubuntu:

By default, Ubuntu requires a minimum password length of 4 characters

Say the password is to be modified by the user using passwd. Is there a command for displaying the current password policies for a user (such as the chage command displays the password expiration information for a specific user)?

> sudo chage -l SomeUserName
Last password change                                : May 13, 2010
Password expires                                    : never
Password inactive                                   : never
Account expires                                     : never
Minimum number of days between password change      : 0
Maximum number of days between password change      : 99999
Number of days of warning before password expires   : 7

This is rather than examining various places that control the policy and interpreting them since the process could contain errors. A command that reports the composed policy would be used to check the policy setting steps.

Answer 1

THe policy is found in /etc/pam.d/common-password. Default policy is obscure which is documented in the pam_unix man page. You may want to install pam_cracklib and add some addition policies. Password changes by root generally avoid policies.

If you are not using pam to verify the new password, then the policy will belong to the tool used to change the password. This can happen if you are using LDAP or another external password database and changing the password directly in the database.