Security issue is a challenge for almost all projects, and especially for IoT projects. Since the widespread application of IoT, there have been too many security incidents in the industry.
As the fact standard for IoT communication protocols, the MQTT protocol maintains high security and provides a multi-level security design:
EMQ X MQTT Broker fully supports various security specifications of MQTT protocol. With built-in security functions, it can be used out of the box without programming, and can quickly eliminate the security risks in the project. The EMQ X authentication series will around various levels of security specifications explain how to enable related functions through the configuration of EMQ X to finally achieve corresponding security protection.
This article will around the core concepts related to MQTT connection authentication in EMQ X, introduce the authentication methods supported by EMQ X and the applicable scene. The MQTT related authentication chain, authentication process/principle, and configuration points will be explained through the working mechanism and configuration principles to let you quickly master the EMQ X authentication configuration method.
In EMQ X, the built-in data sources (files, built-in databases), JWT, external mainstream databases, and custom HTTP APIs can be used as authentication data sources.
Connecting data sources and performing authentication are implemented by plugins. Each plugin corresponds to an authentication method. Therefore, users need to enable related plugins before using the authentication function.
When the client connects, the plugin implements the identity authentication of the client by checking whether its username/clientid and password are consistent with the information of the specified data source.
Authentication methods supported by EMQ X:
Built-in data sources
The configuration file, and the built-in database of EMQ X are used to provide an authenticated data source, which is managed through the HTTP API and is simple and lightweight.
The external database can store a large amount of data, and can easily integrate with external device management systems.
JWT authentication can issue authentication information in batches, and HTTP authentication can implement complex authentication logic.
After changing the plugin configuration, you need to restart the plugin to take effect. Some authentication plugins include ACL function.
Any authentication method will eventually return a result:
Anonymous authentication is enabled in the EMQ X default configuration and any client can access EMQ X. When the authentication plugin is not enabled or the authentication plugin does not explicitly allow/deny(ignore) the connection request, EMQ X will decide whether to allow the client to connect based on whether the anonymous authentication is enabled.
Configure the anonymous authentication:
# etc/emqx.conf ## Value: true | false allow_anonymous = true
Please disable anonymous authentication in production environments.
The hash method can be enabled in most EMQ X authentication plugins. Only the password cipher text is saved in the data source to ensure data security.
When the hash method is enabled, the user can specify a salt for each client and configure a salting rule. The password stored in the database is the processed cipher text according to the salting rule and hash method.
Taking MySQL authentication as an example：
Salting rules and hash method configuration：
# etc/plugins/emqx_auth_mysql.conf ## only hash is used without salt auth.mysql.password_hash = sha256 ## salt prefix: use sha256 to encrypt salt + password auth.mysql.password_hash = salt,sha256 ## salt suffix: encrypted password using sha256 + salt auth.mysql.password_hash = sha256,salt ## pbkdf2 with macfun iterations dklen ## macfun: md4, md5, ripemd160, sha, sha224, sha256, sha384, sha512 ## auth.mysql.password_hash = pbkdf2,sha256,1000,20
Taking PostgreSQL authentication as an example, its functional logic is as follows:
The authentication can be performed normally when the salting rules and hash method of the written data are consistent with the configuration of the corresponding plugin. It will invalidate existing authentication data when changing the hashing method.
When enabling multiple authentication methods at the same time, EMQ X will perform chain authentication in the order in which the plugins are opened:
Once authentication succeeds, terminate the authentication chain and allow clients to access
Once authentication fails, terminate the authentication chain and prohibit client access
If Failing to pass until the last authentication method, it is determined according to anonymous authentication configuration
It can improve client authentication efficiency when enabling only one authentication plugin at the same time.
The default port for MQTT TLS is 8883:
listener.ssl.external = 8883
Configure certificates and CAs:
listener.ssl.external.keyfile = etc/certs/key.pem listener.ssl.external.certfile = etc/certs/cert.pem listener.ssl.external.cacertfile = etc/certs/cacert.pem
Note that the
cacert.pem under the default directory of
etc/certs are self-signed certificates generated by EMQ X Broker. Therefore, when testing with a client that supports TLS, you need to configure the above CA certificate
etc/certs/cacert.pem to the client.
The cipher list supported by the server needs to be specified explicitly. The default list is consistent with Mozilla's server cipher list:
listener.ssl.external.ciphers = ECDHE-ECDSA-AES256-GCM-SHA384,ECDHE-RSA-AES256-GCM-SHA384,ECDHE-ECDSA-AES256-SHA384,ECDHE-RSA-AES256-SHA384,ECDHE-ECDSA-DES-CBC3-SHA,ECDH-ECDSA-AES256-GCM-SHA384,ECDH-RSA-AES256-GCM-SHA384,ECDH-ECDSA-AES256-SHA384,ECDH-RSA-AES256-SHA384,DHE-DSS-AES256-GCM-SHA384,DHE-DSS-AES256-SHA256,AES256-GCM-SHA384,AES256-SHA256,ECDHE-ECDSA-AES128-GCM-SHA256,ECDHE-RSA-AES128-GCM-SHA256,ECDHE-ECDSA-AES128-SHA256,ECDHE-RSA-AES128-SHA256,ECDH-ECDSA-AES128-GCM-SHA256,ECDH-RSA-AES128-GCM-SHA256,ECDH-ECDSA-AES128-SHA256,ECDH-RSA-AES128-SHA256,DHE-DSS-AES128-GCM-SHA256,DHE-DSS-AES128-SHA256,AES128-GCM-SHA256,AES128-SHA256,ECDHE-ECDSA-AES256-SHA,ECDHE-RSA-AES256-SHA,DHE-DSS-AES256-SHA,ECDH-ECDSA-AES256-SHA,ECDH-RSA-AES256-SHA,AES256-SHA,ECDHE-ECDSA-AES128-SHA,ECDHE-RSA-AES128-SHA,DHE-DSS-AES128-SHA,ECDH-ECDSA-AES128-SHA,ECDH-RSA-AES128-SHA,AES128-SHA
If you want to use PSK authentication, you need to comment out
listener.ssl.external.ciphers in TLS Authentication, and then configure
#listener.ssl.external.ciphers = ECDHE-ECDSA-AES256-GCM-SHA384,... listener.ssl.external.psk_ciphers = PSK-AES128-CBC-SHA,PSK-AES256-CBC-SHA,PSK-3DES-EDE-CBC-SHA,PSK-RC4-SHA
Then, enable the emqx_psk_file plugin:
$ emqx_ctl plugins load emqx_psk_file
The configuration file for PSK is
etc/psk.txt. A colon
: is used to separate the PSK ID and PSK:
[MQTT X](https://mqttx.app) is a cross-platform MQTT 5.0 desktop test client provided by the world's leading open source IoT middleware provider [EMQ](https://emqx.io) , which supports macOS, Linux, Windows. The user interface of **MQTT X** simplifies the operation logic of the page with the pattern of chatting software. Users can quickly create multiple simultaneous-online MQTT clients to test the connection/publish/subscribe functions of MQTT/TCP, MQTT/TLS and other MQTT protocol features.
In April, EMQ X 4.3-beta.5 release summed up all the fixes has to be done before 4.3.0 release. This allowed us to gradually shift our focuses towards 5.0 development.
The message retention function of [EMQ X MQTT Broker](https://emqx.io) is implemented by the `emqx_retainer` plugin, which is enabled by default. By modifying the configuration of the` emqx_retainer` plugin, you can adjust the EMQ X Broker's retention message Location, restrict the number of retained messages and maximum payload length, and adjust the expiration time of retained messages.