---
title: "Launch Catalyst Functions Shell and Start Tunneling"
url: https://docs.catalyst.zoho.com/en/tools/tunneling/implementation/launch-tunneling/
description: "Catalyst Tunneling allows you to debug Non-HTTPS and Integration functions by routing function calls to your local system using a rever-proxy provider's tunneling URL."
last_updated: 2026-08-17T12:16:04Z
service: All Services
type: general
---

# Launch Catalyst Functions Shell and Start Tunneling

Launch Catalyst function shell using the following CLI command with the `--tunnel` option and specify the port number in which you generated the Tunneling URL.

```sh
catalyst functions:shell --tunnel tunnel-port-number
```

This command will start tunneling your functions.

![catalyst_tunneling_enter_cli_command](https://catalyst-docs-development.zohostratus.in/images/catalyst-extension/tunneling/catalyst_tunneling_enter_cli_command.webp)

If you trigger the function, all the calls made will be routed locally, and you will be able to view their execution logs in the Catalyst CLI.
![catalyst_tunneling_viewing_exec_logs_cli](https://catalyst-docs-development.zohostratus.in/images/catalyst-extension/tunneling/catalyst_tunneling_viewing_exec_logs_cli.webp)

If you attempt to view the *Execution History* of the tunneled function present in the component's section, it will be clearly indicated that the function has been tunneled.
![catalyst_tunneling_view_logs_hihglight](https://catalyst-docs-development.zohostratus.in/images/catalyst-extension/tunneling/catalyst_tunneling_view_logs_hihglight.webp)

If you further click the **view-logs** icon, you will be able to view details such as when and by whom the tunneling was enabled, and disabled.
![catalyst_tunneling_view_logs_log_section](https://catalyst-docs-development.zohostratus.in/images/catalyst-extension/tunneling/catalyst_tunneling_view_logs_log_section.webp)

> **Note:** The logs will only be visible in the Catalyst CLI because the non-HTTPS or Integration function is being executed in the local machine, and not on the Catalyst cloud.

The same information can be found in the [Audit Logs](https://docs.catalyst.zoho.com/en/getting-started/set-up-a-catalyst-project/audit-logs/).

![catalyst_tunneling_audit_logs](https://catalyst-docs-development.zohostratus.in/images/catalyst-extension/tunneling/catalyst_tunneling_audit_logs.webp)

Now, execute the following CLI command to tunnel and debug your functions:

```sh
catalyst functions:shell --tunnel tunnel-port-number --debug port-number
```

![catalyst_tunneling_cli_command_debug](https://catalyst-docs-development.zohostratus.in/images/catalyst-extension/tunneling/catalyst_tunneling_cli_command_debug.webp)

> **Note:** Ensure you provide different port numbers for tunneling and debugging.

If you tunnel your function and choose to debug, you have to implement additional IDE configurations. You can find the steps to configure your IDE's debugger for debugging tunneled functions from this [section](https://docs.catalyst.zoho.com/en/tools/tunneling/implementation/ide-config/java/).