How to Enable SSH Access in a Docker Container Using a CentOS Image

After pulling an Ubuntu image and starting a container, the container is isolated; this guide shows how to bridge communication by configuring SSH using a CentOS image.

Steps

Download the CentOS base image: docker pull centos Create a Dockerfile that installs OpenSSH and sets up users and passwords.

Build a new image from the Dockerfile: docker build -rm -t dys/centos:ssh . Run a container from the new image with port mapping: docker run -d -p 22 dys/centos:ssh Test the SSH connection: ssh [email protected] -p 1035 The Dockerfile content:

FROM centos
MAINTAINER dys "[email protected]"
RUN yum install -y openssh openssh-server openssh-clients
RUN mkdir -p /var/run/sshd
RUN ssh-keygen -t rsa -f /etc/ssh/ssh_host_rsa_key
RUN ssh-keygen -t dsa -f /etc/ssh/ssh_host_dsa_key
RUN /bin/echo 'root:aaaaaa' | chpasswd
RUN useradd dys
RUN /bin/echo 'dys:aaaaaa' | chpasswd
RUN /bin/sed -i 's/.*session.*required.*pam_loginuid.so.*/session optional pam_loginuid.so/g' /etc/pam.d/sshd
RUN /bin/echo -e "LANG=\"en_US.UTF-8\"" > /etc/default/local
EXPOSE 22
CMD /usr/sbin/sshd -D

After building, docker images shows the new dys/centos:ssh image. Running docker ps confirms the container is up, and the port mapping (e.g., 0.0.0.0:1035->22/tcp) allows SSH access.

Connecting with the provided user dys and password aaaaaa logs into the container’s shell, as shown in the screenshots.

The crucial part is writing the Dockerfile; further details will be covered later.