Docker SSH Tunnel

Create a lightweight Alpine Linux based SSH tunnel to a host. Uses pure SSH, no fluff.

Versions

• v1.8, v1.8.2, latest (Dockerfile)
• v1.7, v1.7.2 (Dockerfile)
• v1.6 (Dockerfile)
• v1.5 (Dockerfile)
• v1.4 (Dockerfile)
• v1.3, v1.3.1 (Dockerfile)
• v1.2 (Dockerfile)
• v1.1 (Dockerfile)
• v1.0 (Dockerfile)

For single TCP port applications (database/webserver/debugging access) a SSH tunnel is far faster and simpler than using a VPN like OpenVPN; see this excellent blog post for more info.

For example I use it to create a SSH tunnel from a GCP Kubernetes cluster into an on prem bastion host in order to talk to an on prem MySQL database; it SSHs onto the internal LAN and connects me to the internal on prem MySQL server.

Inspired by https://github.com/iadknet/docker-ssh-client-light and GCP CloudSQL Proxy

Required Parameters

# local port on your machine/k8s cluster
LOCAL_PORT=3306

# remote port from the machine your SSHing into
REMOTE_PORT=3306

# OPTIONAL defaults to 127.0.0.1
REMOTE_SERVER_IP="my.internal.mariadb.server"

# the bastion/host you're connecting to
SSH_BASTION_HOST="bastion.host"

# OPTIONAL defaults to 22
SSH_PORT=2297

SSH_USER="tunnel_user"

Also be sure to inject/mount your private ssh key into the container to /ssh_key/id_rsa

Example

# connect to our mongo server in AWS via a bastion host
# now we can use a connection string like this:
# mongodb://localhost:27017 
# to talk to our AWS mongo install

docker run -it --rm \
-p 27017:27017 \
-e LOCAL_PORT=27017 \
-e REMOTE_PORT=27017 \
-e SSH_BASTION_HOST=34.135.248.162 \
-e REMOTE_SERVER_IP=aws-nlb-mongo-fake.internal-us-east-1.es.amazonaws.com \
-e SSH_USER=ec2-user \
-v ~/.ssh/id_rsa:/ssh_key/id_rsa:ro \
jujhars13/docker-ssh-tunnel

# connection established, now we can mongo away locally
mongo --host localhost --port 27017

TODO

• add example docker-compose.yml to /examples
• add example k8s manifest to /examples

Version

• 2022-08-11 - v1.8 - Removes Bash, Bumps Alpine to v3.16
• 2021-09-12 - v1.8 - Bumps Alpine to v3.15