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Last pushed: a month ago
Short Description
Highly customizable AutoSSH docker container
Full Description


Highly customizable AutoSSH docker container


jnovack/autossh is a small lightweight (8.07MB) image that attempts to
provide a secure way to establish an SSH Tunnel without including your keys in
the image itself or linking to the host.

There's thousands of autossh docker containers, why use this one? I hope you
find it easier to use. It's smaller, more customizable, an automated build, so
it's easy to use, and I hope you learn something!


autossh is a program to start a copy of ssh and monitor it, restarting it as
necessary should it die or stop passing traffic.

Before we begin, I want to define some terms.

  • local - THIS docker container.

  • target - The endpoint and ultimate destination of the tunnel.

  • remote - The 'middle-man', or proxy server you are tunnelling through to
    get to your target.

  • source - The initial endpoint you are starting from that does not have
    access to the target endpoint, but does have access to the remote

The local machine is USUALLY the same as the target but since we are using
Docker, we have to abstract out the local container from the target
endpoint where we want autossh to land. Normally, this is where
autossh is usually run from.

Typically, the target can be on a Home LAN segment without a publicly
addressible IP address; whereas the remote machine has an address that is
reachable by both target and source. And source can only reach remote.

target ---> |firewall| >--- remote ---< |firewall| <--- source             [public.ip.addr]

The target (running autossh) connects up to the remote server and
keeps a tunnel alive so that source can proxy through remote and reach
resources on target. Think of it as "long distance port-forwarding".


To start, you will need to generate an SSH key on the Docker host. This will
ensure the key for the container is separate from your normal user key in the
event there is ever a need to revoke one or the other.

$ ssh-keygen -t rsa -b 4096 -C "autossh"
Generating public/private rsa key pair.
Enter file in which to save the key (/home/jnovack/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/jnovack/.ssh/id_rsa.
Your public key has been saved in /home/jnovack/.ssh/
The key fingerprint is:
00:11:22:33:44:55:66:77:88:99:aa:bb:cc:dd:ee:ff jnovack@yourmom
The key's randomart image is:
+-----[ RSA 4096]-----+
|     _.-'''''-._     |
|   .'  _     _  '.   |
|  /   (_)   (_)   \  |
| |  ,           ,  | |
| |  \`.       .`/  | |
|  \  '.`'""'"`.'  /  |
|   '.  `'---'`  .'   |
|     '-._____.-'     |

Command-line Options

What would a docker container be without customization? I have an extensive
list of environment variables that can be set.

Environment Variables


Specify the usename on the remote endpoint. (Default: root)


Specify the address (ip preferred) of the remote endpoint. (Default:


Specify the port number on the remote endpoint which will serve as the
tunnel entrance. (Default: random > 32768) If you do not want a new port
every time you restart jnovack/autossh you may wish to explicitly set


Specify the address (ip preferred) of the target.


Specify the port number on the target endpoint which will serve as the
tunnel exit, or destination service. Typically this is ssh (port: 22),
however, you can tunnel other services such as redis (port: 6379),
elasticsearch (port: 9200) or good old http (port: 80) and https (port: 443).

Docker Volumes


Mount the key you generated within the Setup step.

-v /path/to/id_rsa:/id_rsa



In the top example ssh-to-docker-host, a tunnel will be made from the docker
container (aptly named autossh-ssh-to-docker-host) to the host running the
docker container.

To use, ssh to fake internet address and you will be
forwarded to (the host running the docker container).

In the lower example, ssh-to-lan-endpoint, a tunnel will be made to a host
on the private LAN of the docker host. sshing to fake internet address will traverse through the docker container through the
docker host, and onto the private lan where the connection will terminate

version: '2.1'

    image: jnovack/autossh
    container_name: autossh-ssh-to-docker-host
      - SSH_HOSTUSER=sshuser
    restart: always
     - /etc/autossh/id_rsa:/id_rsa

    image: jnovack/autossh
    container_name: autossh-ssh-to-lan-endpoint
      - SSH_HOSTUSER=sshuser
      - SSH_TUNNEL_BIND_PORT=22222
    restart: always
      - /etc/autossh/id_rsa:/id_rsa
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