Use Built-in Database

You can use the built-in database of EMQX as a low-cost and out-of-the-box option for password authentication. After enabling, EMQX will save the client credentials in its built-in database (based on Mnesia) and manage data via REST API and Dashboard. This page introduces how to use the EMQX Dashboard and configuration items to configure the authentication using the built-in database.

TIP

Knowledge about basic EMQX authentication concepts

Configure with Dashboard

You can use EMQX Dashboard to set the built-in database for password authentication.

In the EMQX Dashboard, click Access Control -> Authentication from the left navigation menu. On the Authentication page, click Create at the top right corner. Click to select Password-Based as Mechanism and Built-in Database as **Backend **to go to the Configuration tab, as shown below.

UserID Type: Specify the fields for client ID authentication; Options: username, clientid（corresponding to the Username or Client Identifier fields in the CONNECT message sent by the MQTT client).

Password Hash: Select the password hashing algorithm applied to plain-text passwords before results are stored in the database. Available options are plain, md5, sha, sha256, sha512, bcrypt, and pbkdf2. Additional configurations depend on the selected algorithm:

• For md5, sha, sha256 or sha512:
  • Salt Position: Determines how salt (random data) is mixed with the password. Options are suffix, prefix, or disable. You can keep the default value unless you migrate user credentials from external storage into the EMQX built-in database.
  • Resulting hash is represented as a string of hexadecimal characters, and compared case-insensitively with the stored credential.
• For plain:
  • Salt Position: should be disable.
• For bcrypt:
  • Salt Rounds: Defines the number of times the hash function is applied, expressed as 2^{Salt Rounds}, also known as the "cost factor". The default value is 10, with a permissible range of 5 to 10. A higher value is recommended for enhanced security. Note: Increasing the cost factor by 1 doubles the necessary time for authentication.
• For pbkdf2:
  • Pseudorandom Function: Selects the hash function that generates the key, such as sha256.
  • Iteration Count: Sets the number of times the hash function is executed. The default is 4096.
  • Derived Key Length (optional): Specifies the length in bytes of the generated key. If left blank, the length will default to that determined by the selected pseudorandom function.
  • Resulting hash is represented as a string of hexadecimal characters, and compared case-insensitively with the stored credential.

After you finish the settings, click Create.

Configure with Configuration Items

You can also configure the authentication through configuration items.

Example:

{
   backend = "built_in_database"
   mechanism = "password_based"
   password_hash_algorithm {
      name = "sha256",
      salt_position = "suffix"
   }
   user_id_type = "username"
}

Migrate from External Storage to EMQX Built-in Database

To migrate user credentials from external storage to the EMQX built-in database, you can use .csv or .json files for batch import. For operating details, see Import User.