# AWS IoT secure tunneling

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This page was generated from content adapted from the [AWS Developer Guide](https://github.com/awsdocs/aws-iot-docs.git)
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## Configuring a remote device and using IoT agent

* **Note**\
  If you want to deliver the destination client access token to the remote device through methods other than subscribing to the reserved MQTT topic, you might need a destination client access token (CAT) listener and a local proxy. The CAT listener must work with your chosen client access token delivery mechanism and be able to start a local proxy in destination mode.

## Resolving secure tunneling connectivity issues

* **Note**\
  If you're not sure whether the CAT needs to be rotated on the source or destination, you can rotate the CAT on both the source and destination by setting `ClientMode` to ALL when using the `RotateTunnelAccessToken` API. Rotating the CAT doesn't extend the tunnel duration. For example, say the tunnel duration is 12 hours and the tunnel has already been open for 4 hours. When you rotate the access tokens, the new tokens that are generated can only be used for the remaining 8 hours.
* **Note**\
  Using client tokens to reuse the CAT is not recommended. We recommend that you use the `RotateTunnelAccessToken` API instead to rotate the client access tokens to reconnect to the tunnel.


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