serversideup/docker-ssh repository overview

⁠Introduction

serversideup/docker-ssh is a hardened SSH server container based on Debian. It works great if you need to create a secure tunnel into your cluster.

⁠Features

• 🐧 Debian-based - Get a lightweight experience, while still having Bash
• 📂 rsync included - Easily back up or sync data from your Docker volumes over SSH
• 🤝 Key-based auth via ENV - Grant access with the AUTHORIZED_KEYS environment variable
• ⛔️ Block IPs via ENV - Block access with the ALLOWED_IPS environment variable
• 🔒 Unprivileged user - All SSH connections are made as an unprivileged user
• 🔑 Set your own PUID and PGID - Have the PUID and PGID match your host user
• 🔐 Hardened SSH - Prevent bot attacks and ensure quality security
• 📦 DockerHub and GitHub Container Registry - Choose where you'd like to pull your image from
• 🤖 Multi-architecture - Every image ships with x86_64 and arm64 architectures

⁠Usage

This is a list of the docker images this repository creates:

Image	Image Size	Description
serversideup/docker-ssh		A hardened SSH server based on Debian Bookworm.

⁠Usage instructions

All variables are documented here:

⁠1. Set your AUTHORIZED_KEYS environment variable or provide a /authorized_keys file

You can provide multiple keys by loading the contents of a file into an environment variable.

AUTHORIZED_KEYS="$(cat .ssh/my_many_ssh_public_keys_in_one_file.txt)"

Or you can provide the authorized_keys file via a volume. Ensure the volume references matches the path of /authorized_keys. The image will automatically take the file from /authorized_keys and configure it for use with your selected user.

ℹ️ NOTE: If both a file and variable are provided, the image will respect the value of the variable over the file.

⁠2. Set your ALLOWED_IPS environment variable

Set this in the same context of AllowUsers⁠This example shows a few scenarios you can do:

ALLOWED_IPS="AllowUsers *@192.168.1.0/24 *@172.16.0.1 *@10.0.*.1"

⁠3. Forward your external port to 2222 on the container

You can see I'm forwarding 12345 to 2222.

docker run --rm --name=ssh --network=web -p 12345:2222 localhost/ssh

This means I would connect with:

ssh -p 12345 [email protected]

⁠Working example with MariaDB + SSH + Docker Swarm

Here's a perfect example how you can use it with MariaDB. This allows you to use Sequel Pro or TablePlus to connect securely into your database server 🥳

⁠Example using ALLOWED_IPS variable:

services:
  mariadb:
    image: mariadb:10.11
    networks:
      - database
    environment:
        MARIADB_ROOT_PASSWORD: "myrootpassword"
  ssh:
    image: serversideup/docker-ssh
    ports:
      - target: 2222
        published: 2222
        mode: host
    # Set the Authorized Keys of who can connect
    environment:
      AUTHORIZED_KEYS: >
        "# Start Keys
         ssh-ed25519 1234567890abcdefghijklmnoqrstuvwxyz user-a
         ssh-ed25519 abcdefghijklmnoqrstuvwxyz1234567890 user-b
         # End Keys"
      # Lock down the access to certain IP addresses
      ALLOWED_IPS: "AllowUsers [email protected]"
    networks:
        - database

networks:
  database:

⁠Example using $SSH_USER_HOME/.ssh/authorized_keys file:

services:
  mariadb:
    image: mariadb:10.11
    networks:
      - database
    environment:
        MARIADB_ROOT_PASSWORD: "myrootpassword"

  ssh:
    image: serversideup/docker-ssh
    ports:
      - target: 2222
        published: 2222
        mode: host
    # Set the Authorized Keys of who can connect
    environment:
      # Lock down the access to certain IP addresses
      ALLOWED_IPS: "AllowUsers [email protected]"
    configs:
      - source: ssh_authorized_keys
        # Mount the file to "/authorized_keys". The image will handle everything else
        target: /authorized_keys
        mode: 0600
    networks:
        - database

# Define the config to be used
configs:
  ssh_authorized_keys:
    file: ./authorized_keys

networks:
  database:

⁠Working example: Backing up a Docker volume with rsync

Because rsync is included in the image, you can mount any Docker volume into the SSH container and pull the data down to your local machine (or push it back up) over a secure SSH tunnel.

⁠1. Mount the volume you want to back up

Attach the volume to a path the SSH user can read. In this example we mount the app_data volume to /data inside the container as read-only:

services:
  ssh:
    image: serversideup/docker-ssh
    ports:
      - target: 2222
        published: 2222
        mode: host
    environment:
      AUTHORIZED_KEYS: >
        "ssh-ed25519 1234567890abcdefghijklmnoqrstuvwxyz user-a"
      ALLOWED_IPS: "AllowUsers [email protected]"
    volumes:
      - app_data:/data:ro

volumes:
  app_data:
    external: true

⁠2. Pull the data down with rsync

From your local machine, use rsync over SSH to copy the contents of the volume to a local directory:

rsync -avz -e "ssh -p 12345" [email protected]:/data/ ./app_data-backup/

⁠Resources

• DockerHub⁠ to browse the images.
• Discord⁠ for friendly support from the community and the team.
• GitHub⁠ for source code, bug reports, and project management.
• Get Professional Help⁠ - Get video + screen-sharing help directly from the core contributors.

⁠Contributing

As an open-source project, we strive for transparency and collaboration in our development process. We greatly appreciate any contributions members of our community can provide. Whether you're fixing bugs, proposing features, improving documentation, or spreading awareness - your involvement strengthens the project. Please review our code of conduct⁠ to understand how we work together respectfully.

• Bug Report: If you're experiencing an issue while using these images, please create an issue⁠.
• Feature Request: Make this project better by submitting a feature request⁠.
• Documentation: Improve our documentation by submitting a documentation change⁠.
• Community Support: Help others on GitHub Discussions⁠ or Discord⁠.
• Security Report: Report critical security issues via our responsible disclosure policy⁠.

Need help getting started? Join our Discord community and we'll help you out!

⁠Our Sponsors

All of our software is free an open to the world. None of this can be brought to you without the financial backing of our sponsors.

⁠Black Level Sponsors

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⁠Individual Supporters

⁠About Us

We're Dan⁠ and Jay⁠ - a two person team with a passion for open source products. We created Server Side Up⁠ to help share what we learn.

Dan Pastori	Jay Rogers

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• 🙋 Community⁠ - Get friendly help from our community members.
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