HiveMQ File Role based Access Control Extension

Purpose

The File Authentication and Authorization Extension implements Access Control based on a configuration file.

This extension implements the configuration for authentication and authorization rules via XML-file. These mechanism are important to protect a MQTT deployment, and the data which is exchanged, from unwanted access.

The extension provides fine-grained control on a topic level to limit clients to specific topics and specific actions (publish or subscribe). Substitution rules for clientId and username allow for dynamic roles to be applied to multiple clients, while still limiting each client to "their own" topics.

Features

• Username and password based authentication for MQTT Clients

• Fine-grained access control on a topic-filter level

• Role based permission management

• Automatic Substitution of client identifier and username

• Runtime reload for Credentials and Roles

• Support for Hashed or Plain-text passwords

• Tooling to generate salted password hashes

• Option to define a set of listeners the extension is used for

Installation

• Download the extension from the HiveMQ Marketplace.

• Copy the content of the zip file to the extensions folder of your HiveMQ nodes.

• Modify the extension-config.xml and credentials.xml files for your needs.

First Steps

Install the extension. The users and roles from the example configuration files are now applied to all new MQTT connections.

Next Steps

Setup your custom Users and Roles in the credentials configuration and configure the extension for your specific use case.

Caution

Because client identifier and usernames can be used for substitution in the permissions, MQTT wildcard characters # and + are prohibited for client identifier and usernames when this extension is used. MQTT connections which include these characters are denied by this extension.

Configuration

This extension has two configuration files. The extension configuration file (extension-config.xml) that includes the general configuration for the extension itself. And the credentials configuration file (credentials.xml) that includes the configuration of Users, Roles and Permissions.

The credentials configuration file is watched for changes and reloaded at runtime if necessary. If the credentials configuration file has changed and contains a valid configuration, then the previous configuration is automatically archived to an archive folder credentials-archive inside the extension folder. So that changes can be tracked and rolled-back if needed. If the new credentials configuration is invalid the current configuration is maintained.

Note	The permissions for connected clients are not changed, only new connecting clients are affected.

Credentials Configuration

The credentials configuration includes the following settings.

Example credentials.xml

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<file-rbac>
    <users>
        <user>
            <name>user1</name>
            <!--- password hash for "pass1" -->
            <password>WFNQUVB0UkxjM04xa0hSR1BQNGhuOTJKVzdlbXA4bjk=:100:FY12nwpUEbBK9EKQ/Aw/rQKSoA7jXsC0HKELwU2mLCVU39bJVK0zf4NemuFeDOHPO4BW1nOjxi6NporkC6rUog==</password>
            <roles>
                <id>role1</id>
            </roles>
        </user>
        <user>
            <name>admin-user</name>
            <!-- password hash for "admin-password" -->
            <password>Vjc1a0lxQ3Nvb0ljNFVHNE9WRnM3RG1IZmdNUFcwVGY=:100:PL2FLqfpdhONG7qXjAMmdVn4wlMiXnypdXiFW09zqorFhKgoiixFQw2EVJJfE9Zn79q45V7Xpc6JeKLp0ntmYA==</password>
            <roles>
                <id>role1</id>
                <id>superuser</id>
            </roles>
        </user>
    </users>
    <roles>
        <role>
            <id>role1</id>
            <permissions>
                <permission>
                    <!-- PUBLISH and SUBSCRIBE to all topics below "data/<clientid>/" -->
                    <topic>data/${{clientid}}/#</topic>
                </permission>
                <permission>
                    <!-- PUBLISH to topic "outgoing/<clientid>", retained only-->
                    <topic>outgoing/${{clientid}}</topic>
                    <activity>PUBLISH</activity>
                    <retain>RETAINED</retain>
                </permission>
                <permission>
                    <!-- SUBSCRIBE to topic "incoming/<username>"-->
                    <topic>incoming/${{username}}/actions</topic>
                    <activity>SUBSCRIBE</activity>
                </permission>
            </permissions>
        </role>
        <role>
            <id>superuser</id>
            <permissions>
                <permission>
                    <!-- Allow everything -->
                    <topic>#</topic>
                </permission>
            </permissions>
        </role>
    </roles>
</file-rbac>

User Configuration

Configuration	Description
name	Username that is presented by the client in the MQTT CONNECT packet.
password	Password that is presented by the client in the MQTT CONNECT packet. Plain text or hashed passwords are supported.
roles	List of IDs of a role which is defined in the same configuration file. The permissions of these roles are applied to the user.

Hashed password strings for the credentials configuration can be generated by running the included password generator tool with the following command, from inside the extension folder.

Example Usage

java -jar hivemq-file-rbac-extension-4.5.3.jar -p mypassword

This tool can be used to generate salted password hashes for the extension credentials file (credentials.xml). A custom salt can be passed with the -s parameter, by default a random salt is generated. The amount of hashing iteration can be specified with the -i parameter.

Example with hashed password

<user>
    <name>user1</name>
    <!--- password hash for "pass1" -->
    <password>TUh5SWZlWmRNNzJQeXU0UkF2QmVKZXBBWFl6VU1Jc28=:gDR4bZ8kABBEL0WBflf09IMJahRlb1KGL2wJydlyWElfIu1F65SSU+RZZpjzy+vT4dDPJxiBSHM07wr56+bKsA==</password>
    <roles>
        <id>role1</id>
    </roles>
</user>

Example with plain text password

<user>
    <name>user1</name>
    <password>pass1</password>
    <roles>
        <id>role1</id>
    </roles>
</user>

Role Configuration

Configuration	Description
id	The ID for this role.
permissions	A list of permissions which are applied for this role. Permissions are applied and checked by HiveMQ in the order they appear in the configuration file.

Permission Configuration

Configuration	Default	Description
topic	-	The topic on which this permission should apply. Can contain standard MQTT wildcards # and +. Also, special substitution with ${{clientid}} and ${{username}} is supported.
activity	ALL	The activity which this client can perform on this topic. Can be PUBLISH, SUBSCRIBE or ALL.
qos	ALL	The MQTT QoS which this client can publish/subscribe with on this topic. The value can be ZERO, ONE, TWO, ZERO_ONE, ONE_TWO, ZERO_TWO or ALL.
retain	ALL	If a message published on this topic can/must be retained. Values are NOT_RETAINED, RETAINED or ALL. This setting is only relevant for PUBLISH messages.
shared-subscription	ALL	If a subscription on this topic can/must be a shared subscription. Values are SHARED, NOT_SHARED or ALL. This setting is only relevant for SUBSCRIBE messages.
shared-group	#	Limits the Shared Subscription group name for a subscription. Values are # to match all or a specific string value. This setting is only relevant for SUBSCRIBE messages that include a Shared Subscription.

Substitution

The special markers ${{clientid}} and ${{username}} in the topic filter for a permission are automatically replaced by the extension with the client identifier and username of the client for which authorization is performed. This allows to configure a permission that applies to multiple clients, but always contains their specific client identifier or username in the topic. Limiting each client to "their own" topics.

Extension Configuration

The credentials configuration includes the following settings.

Example extension-config.xml

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<extension-configuration>

    <!-- Reload interval for credentials in seconds -->
    <credentials-reload-interval>60</credentials-reload-interval>

    <!-- Optional list of names of listeners this extension is used for
    <listener-names>
        <listener-name>my-listener</listener-name>
        <listener-name>my-listener-2</listener-name>
    </listener-names> -->

    <!-- If the credentials file is using HASHED or PLAIN passwords -->
    <password-type>HASHED</password-type>

    <!-- Use this option to toggle the behaviour in case authentication by this extension failed.
         false (default) -> client don't get authenticated
         true            -> instead of failing the authentication we delegate the decision to the next extension-->
    <!--next-extension-instead-of-fail>true</next-extension-instead-of-fail-->

</extension-configuration>

Configuration	Default	Description
credentials-reload-interval	60	Regular interval in seconds, in which the credentials.xml configuration file is checked for changes and reloaded.
listener-names	null	List of names of listeners, this extension will be used for. See HiveMQ config details.
password-type	HASHED	How passwords are stored in the credentials.xml configuration file. Can either bei PLAIN for plain text passwords, or HASHED for a salted password hash.
next-extension-instead-of-fail	false	The outcome in case the RBAC could not authenticate the client successfully. If set to false, the client will get not authenticated (ConnAck packet with error code). If true then the RBAC extension delegates the decision to the next extension with an authentication implemented, in case no other extension exists we fail the authentication.

Note	The listener-names feature requires the use of at least HiveMQ 4.1 / HiveMQ CE 2020.1

Need Help?

If you encounter any problems, we are happy to help. The best place to get in contact is our support.

Contributing

If you want to contribute to HiveMQ File RBAC Extension, see the contribution guidelines.

License

HiveMQ File RBAC Extension is licensed under the APACHE LICENSE, VERSION 2.0. A copy of the license can be found here.