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SSHD Install Script

Adds a SSH server into a container so that you can use an external terminal, sftp, or SSHFS to interact with it.

Script status: Stable

OS support: Debian 9+, Ubuntu 16.04+, and downstream distros.

Maintainer: The VS Code and GitHub Codespaces teams

Syntax

./sshd-debian.sh [SSH Port] [Non-root user] [Start SSHD now flag] [New password for user] [Fix environment flag]
Argument Default Description
SSH port 2222 Port to host SSH server on. 22 is frequently in use, so using a different port is recommended.
Non-root user automatic Specifies a user in the container other than root that will use SSH. A value of automatic will cause the script to check for a user called vscode, then node, codespace, and finally a user with a UID of 1000 before falling back to root.
Start SSHD now flag false Flag (true/false) that specifies whether the SSH server should be started after the script runs.
New password for user skip Sets a new password for the specified non-root user. A value of skip will skip this step. A value of random will generate a random password and print it out when the script finishes.
Fix environment flag true Connections using the SSH daemon use "fresh" login shells that will not contain any environment or PATH updates made in the image. By default the script will wire into login shell creation, add any environment variables not already set, and base the PATH off of what was set in the Dockerifle. Set to false if you experience unexpected problems.

Usage

This script can be used either ad-hoc in an already running container or in a Dockerfile.

Usage when this script is already installed in an image

The SSH script is included in the default Codespaces image (codespaces-linux) that is used in Codespaces when you do not have a custom devcontainer.json. It may also be in images you or your organization has created. Here's how to enable SSH in these cases.

Usage:

  1. The first time you've started the codespace, you will want to set a password for your user. If running as a user other than root, and you have sudo installed:

    sudo passwd $(whoami)

    Or if you are running as root:

    passwd

  2. Open the Ports tab next to the Terminal tab, select Forward port and enter port 2222. Take note of the local address port number if different than 2222.

  3. Your container/codespace now has a running SSH server in it. Use a local terminal (or other tool) to connect to it using the command and password from step 2. e.g.

    ssh -p 2222 -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -o GlobalKnownHostsFile=/dev/null codespace@localhost

    ...where codespace above is the user you are running as in the container (e.g. codespace, vscode, node, or root) and 2222 after -p is the local address port from step 2.

    The “-o” arguments are optional, but will prevent you from getting warnings or errors about known hosts when you do this from multiple containers/codespaces.

  4. Next time you connect to your container/codespace, just repeat steps 2 and 3 and use the same password you set in step 1.

Usage in a Dockerfile

You can add this script to your own Dockerfile as follows.

Usage:

  1. Add sshd-debian.sh to .devcontainer/library-scripts

  2. Add the following to your .devcontainer/Dockerfile:

    COPY library-scripts/sshd-debian.sh /tmp/library-scripts/
RUN apt-get update && bash /tmp/library-scripts/sshd-debian.sh
ENTRYPOINT ["/usr/local/share/ssh-init.sh"]
CMD ["sleep", "infinity"]

    The ENTRYPOINT script can be chained with another script by adding it to the array after ssh-init.sh.

  3. And the following to .devcontainer/devcontainer.json:

    "forwardPorts": [2222],
"overrideCommand": false

  4. The first time you've started the container / codespace, you will want to set a password for your user (assuming you didn't set it using the script). If running as a user other than root, and you have sudo installed:

    sudo passwd $(whoami)

    Or if you are running as root:

    passwd

  5. Connect to the container or codespace using VS Code. You can now SSH into the container on port 2222. For example, if you are in the container as the vscode user, run the following command in a local terminal:

    ssh -p 2222 -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -o GlobalKnownHostsFile=/dev/null vscode@localhost

    ...where vscode above is the user you are running as in the container (e.g. codespace, vscode, node, or root).

    The “-o” arguments are optional, but will prevent you from getting warnings or errors about known hosts when you do this from multiple containers/codespaces.

If you are unable to connect, it's possible SSH is available on a different local port because 2222 was busy. Open the Ports tab next to the Terminal tab, take note of the local address port for port 2222 in the container and update -p 2222 to match.

Ad-hoc Usage

If you already have a running container, you can use the script to spin up SSH inside it.

  1. Connect to the container or codespace using VS Code.

  2. Open a terminal in VS Code and run the following if you're connected as a non-root user and sudo is installed:

    sudo bash -c "$(curl -sSL https://raw.githubusercontent.com/microsoft/vscode-dev-containers/main/script-library/sshd-debian.sh)" -- 2222 $(whoami) true random

    Or if running as root:

    bash -c "$(curl -sSL https://raw.githubusercontent.com/microsoft/vscode-dev-containers/main/script-library/sshd-debian.sh)" -- 2222 $(whoami) true random

  3. Take note of the password that was generated and the SSH command.

  4. Open the Ports tab next to the Terminal tab, select Forward port and enter port 2222. Take note of the local address port number if different than 2222.

  5. Your container/codespace now has a running SSH server in it. Use a local terminal (or other tool) to connect to it using the command and password from step 2. e.g.

    ssh -p 2222 -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null vscode@localhost

    ...where vscode above is the user you are running as in the container (e.g. codespace, vscode, node, or root) and 2222 after -p is the local address port from step 4.

    The “-o” arguments are optional, but will prevent you from getting warnings or errors about known hosts when you do this from multiple containers/codespaces.

  6. Next time you connect, you can spin up the SSH server again by running /usr/local/share/sshd-init.sh in a terminal in the container/codespace and using the same command / password.

Using SSHFS

SSHFS allows you to mount a remote filesystem to your local machine with nothing but a SSH connection. Here's how to use it with a dev container.

  1. Follow the steps in one of the previous sections to ensure you can connect to the dev container using the normal ssh client.

  2. Install a SSHFS client.

    • Windows: Install WinFsp and SSHFS-Win.
    • macOS: Use Homebrew to install: brew install macfuse gromgit/fuse/sshfs-mac
    • Linux: Use your native package manager to install your distribution's copy of the sshfs package. e.g. sudo apt-get update && sudo apt-get install sshfs

  3. Mount the remote filesystem.

    • macOS / Linux: Use the sshfs command to mount the remote filesystem. The arguments are similar to the normal ssh command but with a few additions. For example:

      mkdir -p ~/sshfs/devcontainer
sshfs "vscode@localhost:/workspaces" "$HOME/sshfs/devcontainer" -p 2222 -o follow_symlinks -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -o GlobalKnownHostsFile=/dev/null -C

      ...where vscode above is the user you are running as in the container (e.g. codespace, vscode, node, or root) and 2222 after the -p is the same local port you used in the ssh command in step 1.

    • Windows: Press Window+R and enter the following in the "Open" field in the Run dialog:

      \\sshfs.r\vscode@localhost!2222\workspaces

      ...where vscode above is the user you are running as in the container (e.g. codespace, vscode, node, or root) and 2222 after the ! is the same local port you used in the ssh command in step 1.

  4. Your dev container's filesystem should now be available in the ~/sshfs/devcontainer folder on macOS or Linux or in a new explorer window on Windows.