Access Control List

Access Control List (ACL) provides a more fine-grained approach to authorization. It defines rules that are matched from top to bottom. Once a rule is matched, its permission is applied, and the remaining rules are ignored.

Configuration Items

Name	Type	Required	Description
permit	enum	Yes	permission: allow ,deny
action	enum	No	operation : publish, subscribe, pubsub
topics	Array[String]	No	Array of Topic
username	String	No	Username: "#" means all users
clientid	String	No	ClientID: "#" means all client IDs
and	Array[Object]	No	AND operator
or	Array[Object]	No	OR operator

Configuration Example

This configuration defines various rules for different users and topics, providing a flexible mechanism for managing permissions. Please write the rules in the correct format into the nanomq_acl.conf file and include it in nanomq.conf, as described in the Access Control Introduction. example: acl = {include "/etc/nanomq_acl.conf"}

rules = [
  ## Allow MQTT client using username "dashboard"  to subscribe to "$SYS/#" topics
  {"permit": "allow", "username": "dashboard", "action": "subscribe", "topics": ["$SYS/#"]}

  ## Deny "All Users" subscribe to "$SYS/#" "#" Topics
  {"permit": "deny", "username": "#", "action": "subscribe", "topics": ["$SYS/#", "#"]}

  ## Allow any other publish/subscribe operation
  {"permit": "allow"}
]

${clientid} and ${username} can be used as placeholders in the topic item. When a client with ID as nmq_c triggers the authorization check, t/${clientid} matches the topic t/nmq_c precisely.

Configure in KV format

Users wishing to use the KV configuration format can refer to the following structure and write their configurations into the nanomq_old.conf file. The relevant settings will take effect after NanoMQ is restarted.

• For a complete list of configuration options, refer to Configuration Description - v013

Syntax:

acl.rule.<No>=<Spec>

Example

## Allow MQTT client using username "dashboard"  to subscribe to "$SYS/#" topics
acl.rule.1={"permit": "allow", "username": "dashboard", "action": "subscribe", "topics": ["$SYS/#"]}

## Deny "All Users" subscribe to "$SYS/#" "#" Topics
acl.rule.2={"permit": "deny", "username": "#", "action": "subscribe", "topics": ["$SYS/#", "#"]}

## Allow any other publish/subscribe operation
acl.rule.3={"permit": "allow"}