Integrate with Redis

EMQX supports integrating with Redis for password authentication. EMQX Redis authenticator currently supports connecting to running in three different modes, which are Single, Redis Sentinel and Redis Cluster. This section gives detailed instructions on the data schema supported and on how to configure with EMQX Dashboard and configuration file.

Prerequisite:

Knowledge about basic EMQX authentication concepts

Data Schema and Query Statement

Redis authentication works with credentials stored as Redis hashes with predefined field names:

• password_hash: required; password (in plain text or hashed) stored in the database;
• salt: optional; salt = "" or just remove this field to indicate no salt value will be added;
• is_superuser: optional; flag if the current client is a superuser; default: false.

For example, if we want to add a document for a superuser (is_superuser: true) with username user123, password secret, prefixed salt salt, and password hash sha256, the query statement should be:

>redis-cli
127.0.0.1:6379> HSET mqtt:user123 is_superuser 1 salt salt password_hash ac63a624e7074776d677dd61a003b8c803eb11db004d0ec6ae032a5d7c9c5caf
(integer) 3

The corresponding config params are:

password_hash_algorithm {
    name = sha256
    salt_position = prefix
}

cmd = "HMGET mqtt:${username} password_hash salt is_superuser"

TIP

The name password_hash conveys our preference for storing hashed passwords. But given that Redis doesn't have a MySQL-like as syntax, EMQX 5.0 has kept the password field (in EMQX 4.x) compatible.

So, we can also configure cmd as HMGET mqtt:${username} password salt is_superuser.

Configure with Dashboard

You can use EMQX Dashboard to configure how to use Redis 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 Redis as Backend to go to the Configuration tab, as shown below.

Follow the instructions below on how to configure the authentication:

Connect: Enter the information for connecting to Redis.

• Redis Mode: Select how Redis is deployed, including Single, Sentinel and Cluster.
• Server(s): Specify the Redis server address that EMQX is to connect, if Redis Mode is set to Sentinel or Cluster, you will need to input all Redis servers (separated with a ,) that EMQX is to connect.
• Sentinel Name: Specify the name to use; type: strings; only needed if you set Redis Mode to Sentinel.
• Database: Redis database name; Data type: strings.
• Password (optional): Specify Redis user password.

TLS Configuration: Turn on the toggle switch if you want to enable TLS. For more information on enabling TLS, see Network and TLS.

Connection Configuration: Set the concurrent connections.

• Pool size (optional): Specify the number of concurrent connections from an EMQX node to a Redis server. Default: 8.

Authentication configuration: Configure settings related to authentication:

• Password Hash: the hash function for storing passwords in the database. Options include plain, md5, sha, bcrypt, and pbkdf2. Additional configuration depends on your selected function:
  • For plain, md5, sha, sha256, or sha512:
    • Salt Position: Determine how salt (random data) is added to the password. Options are suffix, prefix, or disable. Keep the default value unless you migrate user credentials from external storage into the EMQX built-in database. Note: Set to disable if plain is selected.
  • For bcrypt:
    • Salt Rounds: Set the number of applications of the hash function, expressed as 2^Salt Rounds, also known as the "cost factor". The default is 10, with a range of 5 to 10. Opting for a higher value enhances security. Note: Increasing the cost factor by 1 doubles the necessary time for authentication.
  • For pkbdf2:
    • Pseudorandom Function: Select the hash function for key generation, such as sha256.
    • Iteration Count: Specify the number of iterations. Default: 4096.
    • Derived Key Length (optional): Set the desired length of the generated password. If left unspecified, the length will be determined by the selected pseudorandom function.
• CMD: Redis query command.

After you finish the settings, click Create.

Configure with Configuration Items

You can configure the EMQX Redis authenticator with EMQX configuration items.

Redis authentication is identified with mechanism = password_based and backend = redis.

EMQX supports working with three kinds of Redis installation.

{
  mechanism = password_based
  backend = redis
  enable = true

  redis_type = single
  server = "127.0.0.1:6379"

  password_hash_algorithm {
      name = sha256
      salt_position = suffix
  }

  cmd = "HMGET mqtt_user:${username} password_hash salt is_superuser"
  database = 1
  password = "public"
  auto_reconnect = true
}

{
  mechanism = password_based
  backend = redis
  enable = true

  redis_type = sentinel
  servers = "10.123.13.11:6379,10.123.13.12:6379"
  sentinel = "mymaster"

  password_hash_algorithm {
      name = sha256
      salt_position = suffix
  }

  cmd = "HMGET mqtt_user:${username} password_hash salt is_superuser"
  database = 1
  password = "public"
  auto_reconnect = true
}

{
  mechanism = password_based
  backend = redis
  enable = true

  redis_type = cluster
  servers = "10.123.13.11:6379,10.123.13.12:6379"

  password_hash_algorithm {
      name = sha256
      salt_position = suffix
  }

  cmd = "HMGET mqtt_user:${username} password_hash salt is_superuser"
  password = "public"
  auto_reconnect = true
}