VSI-MOSQUITTO-V0106-2-1.PDF

This document describes the OpenVMS port of Mosquitto 1.6.2, an open-source MQTT message broker for I64 and Alpha platforms.

Overview & Features:

• Mosquitto is a lightweight, publish-subscribe messaging protocol over TCP/IP, supporting MQTT versions 5.0, 3.1.1, and 3.1. It's ideal for remote, low-bandwidth, or small-footprint applications (e.g., sensors, home automation).
• The OpenVMS port includes full functionality from the open-source release, such as SSL/TLS support (using OpenSSL 1.1.1a), bridging, client authentication, and access controls.
• New in this release: An OpenVMS-specific plugin is included for authenticating users against standard OpenVMS SYSUAF credentials.

Installation & Configuration:

• The software is provided as an OpenVMS PCSI kit, installed using $ PRODUCT INSTALL MOSQUITTO.
• Post-installation: Commands must be added to SYSTARTUP_VMS.COM and SYSHUTDWN.COM for automatic broker startup and shutdown. Users should verify the MOSQUITTO$ROOT logical name, check the broker process (named "MOSQUITTO") with SHOW SYSTEM, and examine log files for errors.
• Test utilities (MOSQUITTO_PUB.EXE, MOSQUITTO_SUB.EXE) are included.
• The broker's configuration file (MOSQUITTO$ROOT:[CONF]MOSQUITTO.CONF) can be modified.
• SYSUAF Authentication: To configure, add auth_plugin mosquitto$auth_plugin_vms to MOSQUITTO$ROOT:[CONF]MOSQUITTO.CONF and optionally set allow_anonymous false to disable unauthenticated logins.

Requirements & System Considerations:

• Requires VSI OpenVMS Version 8.4-1H1 or higher, VSI/HPE/MultiNet TCP/IP, and is recommended for installation on an ODS-5-enabled file system.
• The broker requires specific privileges (TMPMBX, NETMBX, BYPASS, SYSPRV, DETACH) and may need adjustment of system quotas (e.g., Maxjobs, Fillm) and the CHANNELCNT system parameter for many connections.
• Alternative installation locations are supported but require manual copying of startup/shutdown scripts.

Known Problems:

• Depending on TCP/IP configuration, it might be necessary to explicitly set the bind_address parameter in MOSQUITTO$ROOT:[CONF]MOSQUITTO.CONF to an IPv4 address or hostname. This prevents the broker from attempting to bind to IPv6 when it's not enabled, which would cause startup failure.

The kit contains all functionality supported by the Open Source Mosquitto 1.6.2 release. Users are encouraged to consult the official Mosquitto documentation for detailed configuration and management.