# MQTT Transmission Write Permissions

**URL:** <https://forum.inductiveautomation.com/t/mqtt-transmission-write-permissions/114116>\
**Category:** Ignition\
**Created:** [February 23, 2026, 3:59am UTC](https://forum.inductiveautomation.com/t/mqtt-transmission-write-permissions/114116 "2026-02-23T03:59:38Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![douglaslawrie0](https://avatars.discourse-cdn.com/v4/letter/d/da6949/32.png) [@douglaslawrie0](https://forum.inductiveautomation.com/u/douglaslawrie0)\
**Post date:** [February 23, 2026, 3:59am UTC](https://forum.inductiveautomation.com/t/mqtt-transmission-write-permissions/114116/1 "2026-02-23T03:59:38Z")

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I want to expose the “Device Control/Rebirth” NCMD metric for my MQTT Transmitters but ensure no other tags can be written to via MQTT so that data consumers can discover metrics, but don’t accidentally get control permissions in my plant. What is the most robust/secure way of achieving this?

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<div class="post-metadata">

**Author:** ![ryan.white](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/ryan.white/32/73193_2.png) [@ryan.white](https://forum.inductiveautomation.com/u/ryan.white)\
**Post date:** [February 23, 2026, 3:31pm UTC](https://forum.inductiveautomation.com/t/mqtt-transmission-write-permissions/114116/2 "2026-02-23T15:31:24Z")

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Assuming the mqtt tags work like regular tags, you can make use of the built in tag security. I would start by changing all your mqtt tags to be read only, except for the ones you wish to be writable. (If you have a lot, `system.tag.getConfiguration` and `system.tag.configure` will be extremely helpful.)

> **[Security Data Properties​ - Tag Properties | Ignition User Manual](https://www.docs.inductiveautomation.com/docs/8.1/platform/tags/tag-properties#security-data-properties)**
>
> Tags are points of data and may have static values or dynamic values that come from an OPC address, an Expression, or a SQL query. The values can be used on screens and in Transaction Groups. Additionally, tags offer a core set of features above and...

> **[Permission Values​ - Tag Properties | Ignition User Manual](https://www.docs.inductiveautomation.com/docs/8.1/platform/tags/tag-properties#permission-values)**
>
> Tags are points of data and may have static values or dynamic values that come from an OPC address, an Expression, or a SQL query. The values can be used on screens and in Transaction Groups. Additionally, tags offer a core set of features above and...

You can then allow write access to only the control members you want, and restrict who can write to those for finer control. Control can be done via assigned roles, security zone, or both.