Bastion with google authenticator

A simple ssh bastion using public keys and google authenticator to keep things safe.

Usage

SSH host keys will be generated on demand upon launch. You might want to store them in a separate data container to have them persist when upgrading or similar. For this purpose the volume /etc/ssh is defined and may used like:

$ docker volume create bastion-keys
$ docker run -v "bastion-keys:/etc/ssh" -p 2222:22 neochrome/bastion:latest

The user bastion is used for connection:

$ ssh bastion@hostname

google-authenticator

When connecting to the bastion, google-authenticator will be run in order to setup two-factor authentication unless existing settings are present.

If you want to share the generated authentication settings between multiple bastions or have them persisted when upgrading or similar, use a volume like this:

$ docker volume create bastion-ga
$ docker run -v "bastion-ga:/bastion" -p 2222:22 neochrome/bastion:latest

If you have existing authentication settings that you want to use, you may mount those as /.google_authenticator and they will be copied in place upon launch.

You may also use a data container to handle both volumes (/etc/ssh and /bastion) together. E.g:

$ docker create --name bastion-data neochrome/bastion:latest
$ docker run --volumes-from bastion-data -p 2222:22 neochrome/bastion:latest

authorized_keys

In order to authenticate, public keys need to be made available to the bastion. This may be done in a couple of different ways:

1. Bind mount your public key file or existing authorized_keys file as /authorized_keys, the container will then copy the authorized_keys file in place and set correct permissions upon launch.
2. Create a derived image (FROM neochrome/bastion:latest) and add the key(s) to /bastion/authorized_keys, don't forget to set owner to bastion:users.
3. Use volume populated with a /bastion/authorized_keys file with correct ownership set and mounted as /bastion.
4. Like 2, but managed in a data container.

motd

The image comes without a /etc/motd file. If you want one, you may either:

1. Add one to a derived image.
2. Mount one at /motd and then the container will copy it in place upon launch.
3. Mount one at /etc/motd.

Contributing

1. Fork it (https://github.com/neochrome/docker-bastion/fork)
2. Create your feature branch (git switch -c my-new-feature)
3. Commit your changes (git commit -am 'feat: some new feature'), make sure to use https://www.conventionalcommits.org/.
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

Releasing

Releases are automated using Release Please.