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Security Features of HiveMQ HiveMQ is designed from the ground up with maximum security in mind. For mission-critical IoT and M2M scenarios, secure end-to-end encrypted communication and advanced authentication and authorization features are essential. HiveMQ gives you the flexibility to enable the specific security features that your deployment requires. If you are unfamiliar with MQTT security concepts, see the MQTT Security Fundamentals blog series. Authentication & Authorization in HiveMQ HiveMQ handles authentication and authorization through security extensions. For example, the HiveMQ Enterprise Security Extension ships as part of the HiveMQ Enterprise MQTT Broker release bundle. For configuration details, see the HiveMQ Security Extension documentation. You can also download the HiveMQ File RBAC community extension from the HiveMQ website or use the open HiveMQ Extension SDK to develop your own security extension. HiveMQ includes a hivemq-allow-all-extension for testing purposes. This extension authorizes all MQTT clients to connect. Before you use HiveMQ in production, you must add an appropriate security extension and remove the hivemq-allow-all-extension. TLS Transport Layer Security (TLS) is a cryptographic protocol that allows secure and encrypted communication at the transport layer between a client application and a server. If you enable a TLS listener in HiveMQ, each client connection for that listener is encrypted and secured by TLS. Multiple listeners You can configure HiveMQ with multiple listeners so HiveMQ can handle secure and insecure connections simultaneously. For more information, see HiveMQ MQTT Listeners. For deployments where MQTT messages contain sensitive information, we strongly recommend that you enable TLS. When configured correctly, TLS makes it extremely difficult for attackers to break the encryption and read packets on the wire. TLS encrypts the complete transport layer, which makes TLS a better choice than custom payload encryption when security is the priority. TLS Overhead Considerations TLS adds CPU and communication overhead. The TLS handshake adds bandwidth and computation overhead when a connection is established. The additional CPU usage is typically negligible on the broker, but can affect constrained devices that are not designed for computation-intensive tasks. If your deployment uses unreliable connections that frequently drop, consider the increased overhead. For more information, see TLS/SSL - MQTT Security Fundamentals. Encryption at Transport Layer vs Encryption at Application Layer Transport layer encryption encrypts the complete connection, including all MQTT messages sent between the client and the server. This ensures that only the connected client can read any message in the communication. Since the payload of the MQTT message remains as raw bytes, full interoperability with other MQTT clients is ensured (including clients that do not use TLS.) All MQTT messages are secured with this method, not only PUBLISH messages. Application layer encryption encrypts the payload of an MQTT PUBLISH message with application-specific encryption. Only clients that know how to decrypt the payload can read the original message payload. Without TLS, the transport is unencrypted and attackers can read raw messages on the wire. However, if the attacker cannot decrypt the payload, the PUBLISH payload remains secure. NOTE: Application layer encryption only protects PUBLISH payloads. Other information such as topic names remains unencrypted, and other MQTT messages such as CONNECT messages cannot be secured with this method. You can combine both encryption methods. If only a few trusted clients need to decrypt specific PUBLISH payloads and you also need to secure all communication, use both methods together. Java Key Stores and Trust Stores Java key stores and Java trust stores are containers for SSL information such as X.509 certificates and keys. Each store is typically persisted in a single file and protected with a master password. Key stores and trust stores are conceptually similar but serve different purposes: Key stores provide credentials. A key store contains a public key certificate and the corresponding private key. HiveMQ uses key stores to protect the private key for SSL connections. Trust stores verify credentials. A trust store contains trusted certificates or certificates signed by a Certificate Authority (CA). Clients that connect to HiveMQ store the server certificate (or the CA certificate if the server certificate is signed by a CA) to identify the server as trusted. If you are unfamiliar with private and public key cryptography, review this topic before you configure SSL. It is possible to use the same file for the key store and trust store. However, to ensure the security of the private key, we strongly recommend that you use separate files. For information on how to create a key store, see HiveMQ Broker How-Tos. PEM certificate files HiveMQ can load TLS certificates, private keys, and CA certificates directly from PEM-encoded files (.pem, .crt, .key). PEM certificate files are an alternative to keystores and truststores and require no keytool conversion. PEM certificate files are not available in the HiveMQ Community Edition. For more information, see PEM Certificate Files. Autoreload HiveMQ reloads key stores, trust stores, and PEM certificate files during runtime for MQTT listeners, the HiveMQ Control Center, and the HiveMQ REST API. You can add or remove client certificates in the truststore without downtime. You can also change the server certificate in the keystore without downtime. If the same master password is used, you can replace the key store and trust store files without downtime. The cluster transport is the exception: it reads its TLS configuration only at startup, so certificate rotation on the cluster transport requires a node restart. Communication Protocol When no explicit SSL/TLS version is set, HiveMQ automatically uses one of the two default-enabled protocols based on client support. TLSv1.2 or TLSv1.3 are recommended because these protocols tend to be more secure. When no explicit TLS version is set, HiveMQ uses TLSv1.2 or TLSv1.3 by default, based on the version the client supports. The default tls-tcp-listener configuration of HiveMQ enables the following TLS protocols by default: HiveMQ default TLS protocols TLSv1.3 TLSv1.2 For security reasons, the Java runtime that HiveMQ requires disables TLSv1 and TLSv1.1 by default. HiveMQ therefore requires TLS 1.2 or later. To support TLSv1 or TLSv1.1, you must do both of the following: Remove the protocol from the jdk.tls.disabledAlgorithms property in the java.security file of the Java runtime that runs HiveMQ (for example, $JAVA_HOME/conf/security/java.security) and restart HiveMQ. Add the protocol to the TLS version configuration of your HiveMQ listener (see example explicit HiveMQ TLS configuration). We strongly discourage the use of TLSv1 and TLSv1.1. To enable only specific protocols, you can use an explicit TLS configuration that is similar to the following example. If necessary, you can also use such an explicit configuration to enable legacy protocols such as TLSv1 and TLSv1.1: Example explicit TLS version configuration <?xml version="1.0"?> <hivemq xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> ... <listeners> ... <tls-tcp-listener> <tls> ... <!-- Enable specific TLS versions manually --> <protocols> <protocol>TLSv1.2</protocol> </protocols> ... </tls> </tls-tcp-listener> </listeners> ... </hivemq> Cipher Suites The security of TLS depends on the cipher suites in use. Usually, JVM vendors enable only secure cipher suites by default. If you need to restrict HiveMQ to specific cipher suites, you can configure them explicitly. HiveMQ enables the following cipher suites by default: Default cipher suites TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA AES256 requires JCE unlimited strength jurisdiction policy files. TLS_RSA cipher suites are disabled by default in Java 21.0.10 and later versions due to lack of forward secrecy. Use ECDHE cipher suites for secure connections. If none of the default cipher suites are supported, the cipher suites that your JVM enables are used. The list of cipher suites that are enabled by default can change with any HiveMQ release. If you depend on specific cipher suites, specify the cipher suites explicitly. Example configuration to set cipher suites for listeners explicitly <?xml version="1.0"?> <hivemq xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> ... <tls> ... <!-- Only allow specific cipher suites --> <cipher-suites> <cipher-suite>TLS_RSA_WITH_AES_128_CBC_SHA</cipher-suite> <cipher-suite>TLS_RSA_WITH_AES_256_CBC_SHA256</cipher-suite> <cipher-suite>SSL_RSA_WITH_3DES_EDE_CBC_SHA</cipher-suite> </cipher-suites> ... </tls> ... </hivemq> Each TLS listener can be configured to have its own list of enabled cipher suites. Native SSL HiveMQ comes prepackaged with an OpenSSL implementation called BoringSSL that is maintained by Google and can be activated on Linux or macOS. The main advantage of native SSL is increased performance compared to standard JVM SSL. Native SSL also provides access to additional cipher suites, including: Stronger AES with GCM The ChaCha20 stream cipher Additional cipher suites with elliptic curve algorithms Limitations: Native SSL is not available on all platforms. If native SSL is not supported on your platform, HiveMQ performs a graceful fallback to the SSL implementation of your JVM. Cluster transport TLS connections cannot use the native SSL implementation. If native SSL is enabled, you cannot disable the SSLv2Hello communication protocol. If you configure cipher suites that are available in OpenSSL but not in JVM SSL, the broker may have no matching cipher suites for any client, and connections cannot be established. To enable HiveMQ Native SSL, use a configuration similar to the following: Example Native SSL configuration <?xml version="1.0"?> <hivemq xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> ... <listeners> ... <tls-tcp-listener> <tls> ... <native-ssl>true</native-ssl> ... </tls> </tls-tcp-listener> </listeners> ... </hivemq> Due to security concerns and to align with the OpenJDK Java Platform, from HiveMQ 4.7 onwards, HiveMQ only enables the following TLS protocols by default for native SSL: TLSv1.3 TLSv1.2 If you need to support legacy TLS versions such as TLSv1 or TLSv1.1 for your Native SSL implementation, explicitly enable the versions in your tls-tcp-listener configuration: Example native SSL configuration with explicit TLS version <?xml version="1.0"?> <hivemq xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> ... <listeners> ... <tls-tcp-listener> <tls> ... <!-- Enable legacy TLS versions manually --> <protocols> <protocol>TLSv1.1</protocol> </protocols> <native-ssl>true</native-ssl> ... </tls> </tls-tcp-listener> </listeners> ... </hivemq> Randomness If it is available, HiveMQ uses /dev/urandom as the default source of cryptographically secure randomness. /dev/urandom is considered secure enough for almost all purposes [1] and has a significantly better performance than /dev/random. If desired, you can revert to /dev/random for your random number generation: Delete the line that starts with the following information from your $HIVEMQ_HOME/bin/run.sh file if you start HiveMQ manually or the -Djava.security.egd=file:/dev/./urandom option from the configuration file of the init service of your choice. JAVA_OPTS="$JAVA_OPTS -Djava.security.egd=file:/dev/./urandom" OCSP stapling The Online Certificate Status Protocol (OCSP) determines the revocation status of an SSL certificate. OCSP is frequently used as an alternative to Certificate Revocation Lists (CRL) because OCSP contains less information and requires less network traffic. The smaller data payload enables more lightweight clients. In client-driven OCSP, each client requests certificate status directly from the OCSP responder. When many clients use client-driven OCSP, the volume of requests can cause the OCSP responder to become a performance bottleneck. Figure 1. A schematic overview of a client-driven OCSP request for SSL certificate status to an OCSP Responder OCSP stapling allows the HiveMQ broker, rather than the client, to make the status request to the OCSP responder. The HiveMQ broker regularly obtains an OCSP response about its own certificate from the OCSP responder, caches the response, and sends it directly to the client in the initial TLS handshake. The client does not need to connect to the OCSP responder directly. OCSP stapling significantly reduces the load on the OCSP responder because a single request per validity period replaces a request per individual client. Figure 2. A schematic overview of OCSP stapling with the HiveMQ broker The caching interval defines how frequently the HiveMQ broker sends requests for new status information. Between requests, the HiveMQ broker caches the last status that was received. If the OCSP responder is not available, HiveMQ temporarily reduces the cache interval to 15 seconds to get status information as soon as possible. Once a successful OCSP response is received, the interval automatically reverts to the configured value. If the HiveMQ broker does not receive a valid response within 30 minutes, the cached response is cleaned up and no OCSP response is sent to the client. However, HiveMQ continues to try to establish a connection with the OCSP responder. HiveMQ initiates requests for status information to the OCSP responder in the following cases: When a TLS listener starts When the configured cache interval expires When a client requires status information and the response is not yet cached If the cached response expires and a new TLS connection is established OCSP Stapling Configuration Properties The <ocsp-stapling> element has the following properties: Name Default Mandatory Description enabled false no Enables OCSP stapling. override-url none no Overrides the URL of the OCSP Responder contained in the server certificate. An override URL must be set if no OCSP URL information is included in the server certificate. cache-interval 3600 no Interval in seconds to cache the OCSP response on the server side from the OCSP stapling responder. OCSP stapling configuration The following configuration enables OCSP stapling for a TLS TCP listener: <?xml version="1.0"?> <hivemq xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <listeners> ... <tls-tcp-listener> <port>8883</port> <bind-address>0.0.0.0</bind-address> <tls> <keystore> <path>/path/to/the/key/store.jks</path> <password>password-keystore</password> <private-key-password>password-key</private-key-password> </keystore> <native-ssl>true</native-ssl> <ocsp-stapling> <enabled>true</enabled> </ocsp-stapling> </tls> </tls-tcp-listener> ... </listeners> </hivemq> Preconditions OCSP stapling is disabled by default. To use OCSP stapling you must set <native-ssl> and <ocsp-stapling><enabled></ocsp-stapling> to true. The following configuration enables OCSP stapling for a TLS TCP listener with a custom cache-interval and override-url: <?xml version="1.0"?> <hivemq xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <listeners> ... <tls-tcp-listener> <port>8883</port> <bind-address>0.0.0.0</bind-address> <tls> <keystore> <path>/path/to/the/key/store.jks</path> <password>password-keystore</password> <private-key-password>password-key</private-key-password> </keystore> <native-ssl>true</native-ssl> <ocsp-stapling> <enabled>true</enabled> <override-url>http://your.ocsp-responder.com:2560</override-url> <cache-interval>3600</cache-interval> </ocsp-stapling> </tls> </tls-tcp-listener> ... </listeners> </hivemq> HiveMQ Audit Log The audit log provides a unified record of all auditing-relevant events. You can use the audit log in several ways: Review all actions performed on the HiveMQ cluster. Satisfy legal and compliance requirements. Provide data for intrusion-prevention software. Track which users accessed which information and when. Audit Log Configuration The audit log is enabled by default. It can be disabled in the HiveMQ configuration file. Audit Log File Location By default, HiveMQ writes the audit log to <HiveMQ Home>/audit/audit.log. To change the audit log folder, use one of the following options: Set the HIVEMQ_AUDIT_FOLDER environment variable. Set the hivemq.audit.folder system property. For more information, see Manually Setting HiveMQ Folders. The audit log contains sensitive information. Be sure to set the filesystem permissions of the audit folder accordingly. Audit Log File Rolling HiveMQ rotates the audit log automatically at midnight each day. The previous audit log file is archived with the filename audit.<yyyy-MM-dd>.log. For example, after two days of operation, the audit folder contains the following files: ├─ audit.2026-04-22.log ├─ audit.2026-04-23.log └─ audit.log HiveMQ does not delete archived audit log files. If you need to remove old audit logs regularly, you must take additional action. For example, set up a scheduled cron job to alleviate data protection concerns or storage constraints. Audit Log Statement Format Each audit log entry uses the following structure: <time><time zone> | user:"<user name>" | IP:"<host address>" | node:"<node name>" | source:"<source>" | <event> Audit Log Statement Arguments Table 1. Log statement arguments Log argument Description time The time when the event occurred. Format: yyyy-MM-ddTHH:mm:ss,SSS time zone The UTC offset of the time zone where the event occurred. Format: ±HH:mm user name The User login that triggered the event. host address The IP address from which the user connected. Supports IPv4 or IPv6 format. node name The identifier of the HiveMQ cluster node on which the event occurred. This name is logged at the start of HiveMQ in the hivemq.log file. For example, "hivemqId": "35yIM". source The origin of the event that generated the audit log entry. The source can be control-center, control-center-v2, or rest-api. When available, additional information is provided in square brackets. For example, control-center [Default Login], control-center-v2 [Clients], or rest-api [/api/v1/mqtt/clients]. event The type of event and additional information for the event. For a list of all events, see Available HiveMQ Audit Log Events. Available HiveMQ Audit Log Events The following events are listed in the audit log: Control Center Events Table 2. HiveMQ Control Center audit log events Event Additional Information Login success Login failure Logout Authentication success Authentication failure Failure reason, if available. Force client disconnect With/without will message and client ID. Invalidate client session Client ID. Add subscription Topic filter, QoS, and client ID. Add shared subscription Topic filter, QoS, and client ID. Remove subscription Topic filter and client ID. Inspect TLS certificate Client ID. Inspect will payload Client ID. Inspect password Client ID. Inspect proxy protocol TLVs Client ID. Create backup Abort backup Upload/import backup Backup file name. Download backup file Backup file name. Delete backup file Backup file name. Restore backup Backup ID. Create trace recording Trace recording name, start time, end time, client filters, topic filters, and packet filters. Stop trace recording Trace recording name. Download trace recording Trace recording name. Delete trace recording Trace recording name. Create new schema Schema ID and version. Delete all schema versions Schema ID and version. Create schema version Schema ID and version. Create script Script ID and version. Delete script Script ID and version. Create script version Script ID and version. Create data policy Data policy ID. Update data policy Data policy ID. Delete data policy Data policy ID. Create behavior policy Behavior policy ID. Update behavior policy Behavior policy ID. Delete behavior policy Behavior policy ID. Create module instance Instance ID, version, and module name. Import custom module Module name. Update module instance Module name and version. Update custom module instance Module name and version. Delete module instance Module name and version. Enabled/Disabled module instance Module name and version. Download module ZIP Module name and source policy ID. Request diagnostic archive Download diagnostic archive Diagnostic archive ID. Delete diagnostic archive Diagnostic archive ID. Created diagnostic archive at Diagnostic archive ID. Set the broker license key Removed the broker license key Revealed the broker license key REST API Events Table 3. HiveMQ REST API audit log events Event Additional Information Obtained paginated list of all clients Obtained client details Client ID. Checked whether the client is connected Client ID. Forced client disconnect Client ID. Forced session delete Client ID. Obtained list of client subscriptions Client ID. Obtained backup details Backup ID. Requested create new backup Backup ID. Requested restore backup Backup ID. Downloaded backup Backup ID. Downloaded list of all backups Requested new diagnostic zip Diagnostic archive ID. Downloaded trace recording Trace recording ID. Obtained list of all trace recordings Created trace recording Trace recording ID. Deleted trace recording Trace recording ID. Stopped trace recording Trace recording ID. Started Data Hub trial mode Obtained the FSM state Client ID. Saved new script Script ID and version. Obtained script Script ID and version. Obtained filtered list of scripts Deleted all versions of script Script ID. Created new schema Schema ID and version. Obtained schema Schema ID and version. Obtained filtered list of schemas Deleted all versions of schema Schema ID. Created new data policy Data policy ID. Updated data policy Data policy ID. Obtained data policy Data policy ID. Obtained filtered list of data policies Obtained paginated list of data policies Deleted all versions of data policy Data policy ID. Created new behavior policy Behavior policy ID. Updated behavior policy Behavior policy ID. Obtained behavior policy Behavior policy ID. Obtained paginated list of behavior policies Deleted behavior policy Behavior policy ID. 1. man urandom(4) and "The plain simple reality of entropy"