When you have something you want to connect beyond the firewall, you can use this Docker image to establish a connection. The usage is very simple.
docker run \
--rm \
-p 3306:3306 \
-v $HOME/.ssh:/ssh \
-e TUNNEL_HOST=example.com \
-e LOCAL_PORT=3306 \
-e REMOTE_HOST=localhost \
-e REMOTE_PORT=3306 \
solo5star/ssh-tunnelYour ~/.ssh/config file should be:
Host example.com
HostName example.com
User solo5star
IdentityFile ~/.ssh/example.pem