Deploy a sshd docker container

Here are some quick steps to deploy a sshd docker container. It will be based on the official CentOS 7 image from docker hub. It can be used as a light-weight ssh jump server.

First, pull the CentOS 7 image

# docker pull centos:7

Next, create a temp directory. Create a Dockerfile inside with the following content.

FROM centos:7
ENV container docker
RUN (cd /lib/systemd/system/sysinit.target.wants/; for i in *; do [ $i == \
systemd-tmpfiles-setup.service ] || rm -f $i; done); \
rm -f /lib/systemd/system/multi-user.target.wants/*;\
rm -f /etc/systemd/system/*.wants/*;\
rm -f /lib/systemd/system/local-fs.target.wants/*; \
rm -f /lib/systemd/system/sockets.target.wants/*udev*; \
rm -f /lib/systemd/system/sockets.target.wants/*initctl*; \
rm -f /lib/systemd/system/basic.target.wants/*;\
rm -f /lib/systemd/system/anaconda.target.wants/*;
VOLUME [ "/sys/fs/cgroup" ]
RUN yum -y install openssh-server openssh-clients
RUN echo root:pass | chpasswd
RUN ssh-keygen -f /etc/ssh/ssh_host_rsa_key -N '' -t rsa
RUN ssh-keygen -f /etc/ssh/ssh_host_ed25519_key -N '' -t ed25519
EXPOSE 22
CMD ["/usr/sbin/sshd", "-D"]

Build the docker image

# docker build -t docker-sshd .

And it’s ready to be ran. Start it up and forward port 22000 to port 22 inside the container

# docker run -p 22000:22 docker-sshd

You can now ssh to the container. Password is set in the Dockerfile.

# ssh -p22000 root@localhost
[root@58e6463d5032 ~]# ssh -V
OpenSSH_7.4p1, OpenSSL 1.0.2k-fips  26 Jan 2017