The Unix Password module
Synopsis

`Module Name:` pam_unix `Author:` `Maintainer:` Authors. `Management groups provided:` account; authentication; password; session `Cryptographically sensitive:` `Security rating:` `Clean code base:` `System dependencies:` `Network aware:`

Overview of module

This is the standard Unix authentication module. It uses standard calls from the system's libraries to retrieve and set account information as well as authentication. Usually this is obtained from the /etc/passwd and the /etc/shadow file aswell if shadow is enabled.

Account component

`Recognized arguments:` `Description: The `Examples/suggested usage: In its accounting mode, this module can be inserted as follows: # # Ensure users account and password are still active # login account required pam_unix.so``

Authentication component

`Recognized arguments:` `Description: The `The default action of this module is to not permit the user access to a service if their When given the argument `The argument, `nodelay`, can be used to discourage the authentication component from requesting a delay should the authentication as a whole fail. The default action is for the module to request a delay-on-failure of the order of one second.```

Remaining arguments, supported by the other functions of this module, are silently ignored. Other arguments are logged as errors through `A helper binary, `unix_chkpwd`, is provided to check the user's password when it is stored in a read protected database. This binary is very simple and will only check the password of the user invoking it. It is called transparently on behalf of the user by the authenticating component of this module. In this way it is possible for applications like xlock to work without being setuid-root. `Examples/suggested usage:` The correct functionality of this module is dictated by having an appropriate `/etc/nsswitch.conf` file, the user databases specified there dictate the source of the authenticated user's record.`

In its authentication mode, this module can be inserted as follows: # # Authenticate the user # login auth required pam_unix.so

Password component

`Recognized arguments:` `Description: This part of the `In the case of conventional unix databases (which store the password encrypted) the `The `The argument `The `The `With the `The `/etc/security/opasswd` in order to force password change history and keep the user from alternating between the same password too frequently. `Examples/suggested usage:` Standard usage: # # Change the users password # passwd password required pam_unix.so````````

An example of the stacking of this module with respect to the pluggable password checking module, `# # Change the users password # passwd password required pam_cracklib.so retry=3 minlen=6 difok=3 passwd password required pam_unix.so use_authtok nullok md5`

Session component

`Recognized arguments:` `Description:` No arguments are recognized by this module component. Its action is simply to log the username and the service-type to `Examples/suggested usage: The use of the session modules is straightforward: # # session opening and closing # login session required pam_unix.so`