====== How to: Access Remote TCP Servers using CloudAccess Adapter ======

The **Mervis CloudAccess Adapter** is a Windows client application that establishes a secure tunnel to your remote PLC. It allows you to access TCP services running on the PLC (such as **SSH**, **Web Servers**, or **Modbus TCP**) as if the device were on your local network.

This guide demonstrates how to configure the Adapter to access an **SSH server** on a remote PLC.

===== Prerequisites =====

Before proceeding, ensure you have the following:
  * **CloudAccess Adapter Binaries**: The Windows client software (usually a `.zip` file).
  * **CloudAccess Credentials**:
    * **User** and **Password** (Specific to the CloudAccess project).
    * **Channel ID**: A unique string (e.g., `iiiii`) identifying the specific service (like SSH) on the PLC.
  * **SSH Client**: Software such as PuTTY, MobaXterm, or Windows Terminal.


The CloudAccess Adapter software and credentials are not publicly downloadable. Please **contact [[en:help:support|Mervis Technical Support]]** to request the Adapter binaries and your specific project credentials.

===== Step 1: Configure appsettings.json =====

The Adapter is controlled entirely by a JSON configuration file. You must map the remote **Channel ID** to a **Local Port** on your computer.

  - Extract the Adapter `.zip` file to a folder (e.g., `C:\Mervis\CloudAccess\`).
  - Open `appsettings.json` in a text editor (like Notepad or VS Code).
  - Locate the ``"Forwarding"`` section inside ``"AdapterEngine"``.

Update the configuration to match the example below. Pay close attention to the **highlighted fields**. You can download this snippet using the link above the code block.

<code javascript appsettings.json>
{
  "urls": "http://*:25011",
  "AdapterEngine": {
    "Forwarding": [
      {
        "ChannelId": "YOUR_CHANNEL_ID_HERE", 
        "Credentials": {
          "User": "YOUR_CA_USERNAME",
          "Password": "YOUR_CA_PASSWORD"
        },
        "Protocol": "Tcp",
        "AdapterClientEndpoint": {
          "Port": 8082, 
          "Ssl": false,
          "Timeout": "00:01:00"
        },
        "DsServerEndpoint": {
          "Host": "cloudaccess.mervis.info",
          "Port": 23000,
          "Ssl": true,
          "ValidateCertificate": false,
          "Timeout": "00:02:30"
        }
      }
    ]
  },
  "Logging": {
    "Console": { "Disabled": false },
    "File": { "Disabled": true },
    "Levels": { "Default": "Trace", "Microsoft": "Warning" }
  },
  "AllowedHosts": "*"
}
</code>

=== Key Configuration Parameters ===
^ Parameter ^ Description ^
| **ChannelId** | The specific ID provided by support that maps to the SSH service on the PLC. |
| **Credentials** | Your CloudAccess User/Password (distinct from your PLC login). |
| **AdapterClientEndpoint / Port** | **The Local Port.** This is the port you will connect to on your PC (e.g., `8082`). You can change this to any free port. |
| **DsServerEndpoint** | Defines the connection to the Mervis Cloud. Typically ``cloudaccess.mervis.info`` on port ``23000``. |

===== Advanced: Mapping Multiple Channels =====

You can define multiple channels to use them in parallel. For example, you can map an **SSH connection** (on local port 8082) and a **PLC Web Server** (on local port 8083) simultaneously.

To do this, add a second block to the ``"Forwarding": [ ... ]`` array. Ensure every block has its unique ``ChannelId`` and a unique local ``Port``.

<code javascript>
"Forwarding": [
  {
    "ChannelId": "SSH_CHANNEL_ID",
    "Credentials": { "User": "...", "Password": "..." },
    "AdapterClientEndpoint": { "Port": 8082 ... },
    "DsServerEndpoint": { ... }
  },
  {
    "ChannelId": "WEB_SERVER_CHANNEL_ID",
    "Credentials": { "User": "...", "Password": "..." },
    "AdapterClientEndpoint": { "Port": 8083 ... }, 
    "DsServerEndpoint": { ... }
  }
]
</code>

===== Step 2: Run the Adapter =====

You can run the adapter temporarily via the console to test the connection.

  - Open **Command Prompt** or **PowerShell**.
  - Navigate to the folder containing the adapter.
  - Run the executable pointing to your config file:

<code powershell>
.\ESG.NetCore.DataSpy.Client.Host.exe --runAsConsole -configFile "appsettings.json"
</code>

**Success:** You should see log output indicating the adapter has started and is listening on your local port (e.g., `127.0.0.1:8082`). **Keep this window open.**

===== Step 3: Connect via SSH Client =====

Now that the tunnel is active, connect your SSH client to your **localhost**.

  - **Host Name (or IP address)**: ``127.0.0.1``
  - **Port**: ``8082`` (Or the value you set in ``AdapterClientEndpoint`` -> ``Port``).
  - **Connection Type**: SSH

When you click **Open**, you will be prompted for login credentials. 

**Login Note:** At this stage, you are logging into the **PLC's Operating System**. Enter the root user and password for the PLC hardware (e.g., Unipi / root), **not** the CloudAccess credentials.

**Windows Terminal Example:**
<code>
ssh unipi@localhost -p 8082 -o ServerAliveInterval=10
</code>

===== Troubleshooting =====

  * **Connection Refused**: Ensure the Adapter console window is still open and running. Check that you are connecting to `127.0.0.1` and the exact port defined in your JSON.
  * **Authentication Failed (Adapter)**: Check the console logs. if you see "Unauthorized" or credential errors, verify the `ChannelId`, `User`, and `Password` in `appsettings.json`.
  * **Port Conflicts**: If the adapter crashes immediately, port `8082` might be in use. Change `"Port": 8082` in the JSON to a different number (e.g., `22222`).