OpenSearch/docs/en/security/authentication/file-realm.asciidoc

[[file-realm]]
=== File-based User Authentication

You can manage and authenticate users with the built-in `file` internal realm.
With the `file` realm users are defined in local files on each node in the cluster.

IMPORTANT:  As the administrator of the cluster, it is your responsibility to
            ensure the same users are defined on every node in the cluster.
            {security} does not deliver any mechanism to guarantee this.

The `file` realm is primarily supported to serve as a fallback/recovery realm. It
is mostly useful in situations where all users locked themselves out of the system
(no one remembers their username/password). In this type of scenarios, the `file`
realm is your only way out - you can define a new `admin` user in the `file` realm
and use it to log in and reset the credentials of all other users.

IMPORTANT: When you configure realms in `elasticsearch.yml`, only the 
realms you specify are used for authentication. To use the 
`file` realm as a fallback, you must include it in the realm chain. 

To define users, {security} provides the <<managing-file-users, users>> command-line
tool. This tool enables you to add and remove users, assign user roles and manage
user passwords.

==== Configuring a File Realm

The `file` realm is added to the realm chain by default. You don't need to
explicitly configure a `file` realm to manage users with the `users` tool.

Like other realms, you can configure options for a `file` realm in the
`xpack.security.authc.realms` namespace in `elasticsearch.yml`.

To configure an `file` realm:

. Add a realm configuration of type `file` to `elasticsearch.yml` under the
`xpack.security.authc.realms` namespace. At a minimum, you must set the realm `type` to
`file`. If you are configuring multiple realms, you should also explicitly set
the `order` attribute. See <<file-realm-settings>> for all of the options you can set
for a `file` realm.
+
For example, the following snippet shows a `file` realm configuration that sets
the `order` to zero so the realm is checked first:
+
[source, yaml]
------------------------------------------------------------
xpack:
  security:
    authc:
      realms:
        file1:
          type: file
          order: 0
------------------------------------------------------------

. Restart Elasticsearch.

[[file-realm-settings]]
===== File Realm Settings

[cols="4,^3,10"]
|=======================
| Setting                 | Required  | Description
| `type`                  | yes       | Indicates the realm type. Must be set to `file`.
| `order`                 | no        | Indicates the priority of this realm within the
                                        realm chain. Realms with a lower order are
                                        consulted first. Although not required, we
                                        recommend explicitly setting this value when you
                                        configure multiple realms. Defaults to
                                        `Integer.MAX_VALUE`.
| `enabled`              | no         | Indicates whether this realm is enabled or
                                        disabled. Enables you to disable a realm without
                                        removing its configuration. Defaults to `true`.
| `cache.ttl`            | no         | Specifies the time-to-live for cached user entries.
                                        A user's credentials are cached for this period of
                                        time. Specify the time period using the standard
                                        Elasticsearch {ref}/common-options.html#time-units[time units].
                                        Defaults to `20m`.
| `cache.max_users`      | no        	| Specifies the maximum number of user entries that
                                        can be stored in the cache at one time. Defaults
                                        to 100,000.
| `cache.hash_algo`      | no        	| Specifies the hashing algorithm that is used for
                                        the cached user credentials. See <<cache-hash-algo,
                                        Cache hash algorithms>> for the possible values.
                                        (Expert Setting).
|=======================

[[managing-file-users]]
==== Managing Users

The `users` command-line tool is located in `ES_HOME/bin/x-pack` and enables
several administrative tasks for managing users:

* <<file-realm-add-user, Adding users>>
* <<file-realm-list-users, Listing users and roles>>
* <<file-realm-manage-passwd, Managing user passwords>>
* <<file-realm-manage-roles, Managing users' roles>>
* <<file-realm-remove-user, Removing users>>

[[file-realm-add-user]]
===== Adding Users

Use the `useradd` sub-command to add a user to your local node.

NOTE: To ensure that Elasticsearch can read the user and role information at
      startup, run `users useradd` as the same user you use to run Elasticsearch.
      Running the command as root or some other user will update the permissions
      for the `users` and `users_roles` files and prevent Elasticsearch from
      accessing them.

[source,shell]
----------------------------------------
bin/x-pack/users useradd <username>
----------------------------------------

A username must be at least 1 character and no longer than 30 characters. The
first character must be a letter (`a-z` or `A-Z`) or an underscore (`_`).
Subsequent characters can be letters, underscores (`_`), digits (`0-9`), or any
of the following symbols `@`, `-`, `.` or `$`.

You can specify the user's password at the command-line with the `-p` option.
When this option is absent, the command prompts you for the password. Omit the
`-p` option to keep plaintext passwords out of the terminal session's command
history.

[source,shell]
----------------------------------------------------
bin/x-pack/users useradd <username> -p <secret>
----------------------------------------------------

Passwords must be at least 6 characters long.

You can define a user's roles with the `-r` option. This option accepts a
comma-separated list of role names to assign to the user.

[source,shell]
-------------------------------------------------------------------
bin/x-pack/users useradd <username> -r <comma-separated list of role names>
-------------------------------------------------------------------

The following example adds a new user named `jacknich` to the `file` realm. The
password for this user is `theshining`, and this user is associated with the
`network` and `monitoring` roles.

[source,shell]
-------------------------------------------------------------------
bin/x-pack/users useradd jacknich -p theshining -r network,monitoring
-------------------------------------------------------------------

For valid role names please see <<valid-role-name, Role Definitions>>.

[[file-realm-list-users]]
===== Listing Users

Use the `list` sub-command to list the users registered with the `file` realm
on the local node.

[source, shell]
----------------------------------
bin/x-pack/users list
rdeniro        : admin
alpacino       : power_user
jacknich       : monitoring,network
----------------------------------

Users are in the left-hand column and their corresponding roles are listed in
the right-hand column.

The `list <username>` sub-command lists a specific user. Use this command to
verify that a user was successfully added to the local `file` realm.

[source,shell]
-----------------------------------
bin/x-pack/users list jacknich
jacknich       : monitoring,network
-----------------------------------

[[file-realm-manage-passwd]]
===== Managing User Passwords

Use the `passwd` sub-command to reset a user's password. You can specify the new
password directly with the `-p` option. When `-p` option is omitted, the tool
will prompt you to enter and confirm a password in interactive mode.

[source,shell]
--------------------------------------------------
bin/x-pack/users passwd <username>
--------------------------------------------------

[source,shell]
--------------------------------------------------
bin/x-pack/users passwd <username> -p <password>
--------------------------------------------------

[[file-realm-manage-roles]]
===== Assigning Users to Roles

Use the `roles` sub-command to manage the roles of a particular user. The `-a`
option adds a comma-separated list of roles to a user. The `-r` option removes
a comma-separated list of roles from a user. You can combine adding and removing
roles within the same command to change a user's roles.

[source,shell]
------------------------------------------------------------------------------------------------------------
bin/x-pack/users roles <username> -a <commma-separate list of roles> -r <comma-separated list of roles>
------------------------------------------------------------------------------------------------------------

The following command removes the `network` and `monitoring` roles from user
`jacknich` and adds the `user` role:

[source,shell]
------------------------------------------------------------
bin/x-pack/users roles jacknich -r network,monitoring -a user
------------------------------------------------------------

Listing the user displays the new role assignment:

[source,shell]
---------------------------------
bin/x-pack/users list jacknich
jacknich       : user
---------------------------------

[[file-realm-remove-user]]
===== Deleting Users

Use the `userdel` sub-command to delete a user.

[source,shell]
--------------------------------------------------
bin/x-pack/users userdel <username>
--------------------------------------------------

==== A Look Under the Hood

All the data about the users for the `file` realm is stored in two files, `users`
and `users_roles`. Both files are located in `CONFIG_DIR/x-pack/` and are read
on startup.

By default, {security} checks these files for changes every 5 seconds. You can
change this default behavior by changing the `resource.reload.interval.high` setting in
the `elasticsearch.yml` file (as this is a common setting in Elasticsearch,
changing its value may effect other schedules in the system).

[IMPORTANT]
==============================
These files are managed locally by the node and are **not** managed
globally by the cluster. This means that with a typical multi-node cluster,
the exact same changes need to be applied on each and every node in the
cluster.

A safer approach would be to apply the change on one of the nodes and have the
`users` and `users_roles` files distributed/copied to all other nodes in the
cluster (either manually or using a configuration management system such as
Puppet or Chef).
==============================

While it is possible to modify these files directly using any standard text
editor, we strongly recommend using the `bin/x-pack/users` command-line tool
to apply the required changes.

[float]
[[users-file]]
===== The `users` File
The `users` file stores all the users and their passwords. Each line in the
`users` file represents a single user entry consisting of the username and
**hashed** password.

[source,bash]
----------------------------------------------------------------------
rdeniro:$2a$10$BBJ/ILiyJ1eBTYoRKxkqbuDEdYECplvxnqQ47uiowE7yGqvCEgj9W
alpacino:$2a$10$cNwHnElYiMYZ/T3K4PvzGeJ1KbpXZp2PfoQD.gfaVdImnHOwIuBKS
jacknich:$2a$10$GYUNWyABV/Ols/.bcwxuBuuaQzV6WIauW6RdboojxcixBq3LtI3ni
----------------------------------------------------------------------

NOTE: {security} uses `bcrypt` to hash the user passwords.

[float]
[[users_defining-roles]]
==== The `users_roles` File

The `users_roles` file stores the roles associated with the users, as in the
following example:

[source,shell]
--------------------------------------------------
admin:rdeniro
power_user:alpacino,jacknich
user:jacknich
--------------------------------------------------

Each row maps a role to a comma-separated list of all the users that are
associated with that role.