SSH directly into a docker container - ssh

Question

i've got some docker conatiners and now I want to access into one with ssh. Thats working I got a connection via ssh to the docker container.
But now I have the problem I don't know with which user I can access into this container?
I've tried it with both users I have on the host machine (web & root). But they don't work.
What to do know?

Answer 1

You can drop directly into a running container with:
$ docker exec -it myContainer /bin/bash
You can get a shell on a container that is not running with:
$ docker run -it myContainer /bin/bash
This is the preferred method of getting a shell on a container. Running an SSH server is considered not a good practice and, although there are some use cases out there, should be avoided when possible.

Answer 2

If you want to connect directly into a Docker Container, without connecting to the docker host, your Dockerfile should include the following:
# SSH login fix. Otherwise user is kicked off after login
RUN echo 'root:pass' | chpasswd
RUN mkdir /var/run/sshd
RUN sed 's#session\s*required\s*pam_loginuid.so#session optional pam_loginuid.so#g' -i /etc/pam.d/sshd
EXPOSE 22
CMD ["/usr/sbin/sshd", "-D"]
Then use docker run with -p and -d flags. Example:
docker run -p 8022:22 -d your-docker-image
You can connect with:
ssh root#your-host -p8022

Answer 3

1.issue the command docker inspect (containerId or name)
You will get a result like this
"IPv6Gateway": "",
"MacAddress": "",
"Networks": {
"my_bridge": {
"IPAMConfig": {
"IPv4Address": "172.17.0.20"
},
"Links": null,
"Aliases": [
"3784372432",
"xxx",
"xxx2"
],
"NetworkID": "ff7ea463ae3e6e6a099e0e044610cdcdc45b21f7e8c77a814aebfd3b2becd306",
"EndpointID": "6be4ea138f546b030bb08cf2c8af0f637e8e4ba81959c33fb5125ea0d93af967",
"Gateway": "172.17.0.1",
"IPAddress": "172.17.0.20",
"IPPrefixLen": 24,
...
read out and copy the IP address from there, connect to it via command ssh existingUser#IpAddress , eg
someExistingUser#172.17.0.20. If the user doesn't exist, create him in the guest image, preferably with the sudo privileges. Probably don't use a root user directly, since as far as I know, that user is preset for connecting to the image via ssh keys, or has a preset password and changing it would probably end up in not being able to ssh connect to the image terminal via a regular way of doing it docker exec -it containerName /bin/bash or docker-compose exec containerName /bin/bash

Answer 4

For some case, enabling SSH in docker container is useful, specially when we want to test some scripts.
The link bellow give a good example how to create and image with ssh enabled and how to get it's IP and connect to it.
Here

Answer 5

If a true SSH connection into the container is needed (i.e. to allow isolated access over the internet), this image from the linuxserver.io guys could be a great solution: https://hub.docker.com/r/linuxserver/openssh-server

Answer 6

Much more robust solution is pulling down nsenter to your sever, then sshing in and running docker-enter from there. That way you don't need to run multiple processes in the container (ssh server + whatever the container is for), or worry about all the extra overhead of ssh users and such (not to mention security concerns).

Answer 7

The idea behind containers is that a container runs a single process so that it can be monitored by the daemon. If this process stops || fails for some reason, it can be restarted depending on your preference in your config. An ssh server is a running process. Therefore, if you need ssh access to your setup, make an ssh server service, which can share Volumes with other containers that are running alongside it in the setup.
To open a shell on a container in a host directly:
Imagine you are on your PC at home and you have a remote machine that runs docker and has running containers, and you want to open a shell on the container directly without "stopping by" on the remote host:
(The -t flag exposes tty)
ssh -t user#remote.host 'docker exec -it running_container_name /bin/bash'
If you are already on the host, like the accepted answer:
(The -i interactive -t tty)
docker exec -it running_container_name /bin/bash