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https://github.com/dmotte/docker-portmap-client

🐳 Docker image you can use to expose one or more TCP ports to the internet using an SSH tunnel
https://github.com/dmotte/docker-portmap-client

client docker docker-compose docker-image dockerfile expose forward forwarding openssh port port-forwarding portmap private-key remote ssh ssh-client tcp tunnel

Last synced: 2 months ago
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🐳 Docker image you can use to expose one or more TCP ports to the internet using an SSH tunnel

Host: GitHub
URL: https://github.com/dmotte/docker-portmap-client
Owner: dmotte
License: mit
Created: 2021-04-01T20:40:06.000Z (over 3 years ago)
Default Branch: main
Last Pushed: 2024-08-25T13:21:43.000Z (4 months ago)
Last Synced: 2024-10-04T07:41:36.047Z (3 months ago)
Topics: client, docker, docker-compose, docker-image, dockerfile, expose, forward, forwarding, openssh, port, port-forwarding, portmap, private-key, remote, ssh, ssh-client, tcp, tunnel
Language: HTML
Homepage: https://hub.docker.com/r/dmotte/portmap-client
Size: 434 KB
Stars: 4
Watchers: 1
Forks: 1
Open Issues: 0
Metadata Files:
- Readme: README.md
- License: LICENSE

Awesome Lists containing this project

README

        # docker-portmap-client

![icon](icon-149.png)

[![GitHub main workflow](https://img.shields.io/github/actions/workflow/status/dmotte/docker-portmap-client/main.yml?branch=main&logo=github&label=main&style=flat-square)](https://github.com/dmotte/docker-portmap-client/actions)

[![Docker Pulls](https://img.shields.io/docker/pulls/dmotte/portmap-client?logo=docker&style=flat-square)](https://hub.docker.com/r/dmotte/portmap-client)

This is a :whale: **Docker image** you can use to expose **one or more TCP ports** to the internet using an **SSH tunnel**.

It works by connecting to a (publicly exposed) SSH server; this can be for example an instance of the **[dmotte/portmap-server](https://github.com/dmotte/docker-portmap-server.git) image**, or an online **SSH tunneling service** such as [portmap.io](https://portmap.io/) or [ngrok.com](https://ngrok.com/).

**Note**: this image runs as an **unprivileged user** (**non-root**).

> :package: This image is also on **Docker Hub** as [`dmotte/portmap-client`](https://hub.docker.com/r/dmotte/portmap-client) and runs on **several architectures** (e.g. amd64, arm64, ...). To see the full list of supported platforms, please refer to the [`.github/workflows/main.yml`](.github/workflows/main.yml) file. If you need an architecture which is currently unsupported, feel free to open an issue.

## Usage

For this section, we assume that you have already set up an SSH server for remote port forwarding (such as [`dmotte/portmap-server`](https://hub.docker.com/r/dmotte/portmap-server)) or you use an online port forwarding service.

This Docker image only supports **SSH public key authentication**, so we assume that you have a :key: **private key file** (hereinafter called `ssh_client_key`) to log in to the server. Please note that the private key file must be kept **unencrypted**, as otherwise the SSH client would ask for the passphrase at startup. Plus, it must be readable by the `portmap` **unprivileged user** inside the container.

Then you'll need an SSH `known_hosts` file containing the **public fingerprint** of your server. To obtain it, you can use the following command (replace the server address and port with yours):

```bash

ssh-keyscan -p2222 10.0.2.15 > known_hosts

```

> **Note**: if you want, you can bypass the known_hosts step by adding `-o StrictHostKeyChecking=no` to the SSH command, but it's **highly discouraged** for security reasons. Please refer to the [OpenSSH client manual page](https://linux.die.net/man/1/ssh) for further information.

Now suppose that you want to publicly expose (using portmap.io) a web service running locally in your LAN at `http://192.168.0.123:8080/`. You can start your portmap client container like this:

```bash

docker run -it --rm \

    -v "$PWD/known_hosts:/known_hosts:ro" \

    -v "$PWD/ssh_client_key:/ssh_client_key:ro" \

    dmotte/portmap-client \

    [email protected] -NvR12345:192.168.0.123:8080

```

For a more complex example, refer to the [`docker-compose.yml`](docker-compose.yml) file.

### Environment variables

List of supported **environment variables**:

| Variable             | Required         | Description                                                      |

| -------------------- | ---------------- | ---------------------------------------------------------------- |

| `KEEPALIVE_INTERVAL` | No (default: 30) | Value for the `ServerAliveInterval` option of the OpenSSH client |

### Volumes

| Internal path     | Required | Description                                                                                                                                                 |

| ----------------- | -------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------- |

| `/known_hosts`    | No       | File containing the SSH server's public fingerprint(s)                                                                                                      |

| `/ssh_client_key` | **Yes**  | Unencrypted private key file that will be used by the OpenSSH client to authenticate itself. It must be readable by the `portmap` user inside the container |

## Development

If you want to contribute to this project, you can use the following one-liner to **rebuild the image** and bring up the **Docker-Compose stack** every time you make a change to the code:

```bash

docker-compose down && docker-compose up --build

```