# MQTT\_Client + CODESYS IIOT Libraries + Certificates

**URL:** <https://www.wago.community/t/mqtt-client-codesys-iiot-libraries-certificates/1439>\
**Category:** CODESYS\
**Tags:** mqtt\
**Created:** [December 19, 2024, 3:41pm UTC](https://www.wago.community/t/mqtt-client-codesys-iiot-libraries-certificates/1439 "2024-12-19T15:41:38Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![NickB](https://avatars.discourse-cdn.com/v4/letter/n/f08c70/32.png) [@NickB](https://www.wago.community/u/NickB)\
**Post date:** [December 19, 2024, 3:41pm UTC](https://www.wago.community/t/mqtt-client-codesys-iiot-libraries-certificates/1439/1 "2024-12-19T15:41:38Z")

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Hi All,

who can share an example how to link the certificate **x.crt** and key **y.key** files to the MQTT\_Client functionblock of the CODESYS IIOT library?

The information on the CODESYS site is not so usefull to me.

 ![image](https://us1.discourse-cdn.com/flex016/uploads/wago/original/2X/e/ecf9254421168b9f1db377899de0ec2f5a2edfd2.png)

Any tips for an online broker that provides these files so we can easily test if it also works?

Thanks

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**Author:** ![WagoFlo](https://avatars.discourse-cdn.com/v4/letter/w/a6a055/32.png) [@WagoFlo](https://www.wago.community/u/WagoFlo)\
**Post date:** [January 13, 2025, 9:02am UTC](https://www.wago.community/t/mqtt-client-codesys-iiot-libraries-certificates/1439/2 "2025-01-13T09:02:54Z")

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Hello NickB,  
you can find a description under the following link [Usage of client certificates from an external certification authority](https://content.helpme-codesys.com/en/LibDevSummary/certificate.html#import-of-client-certificates-with-private-key)