sshd/Dockerfile

FROM ubuntu:latest

ENV     DEBIAN_FRONTEND=noninteractive

RUN     apt update && \
        apt install --no-install-recommends -y \ 
          nano \
          openssh-server \
          openssh-client \
          rsync \
          sudo && \
        rm -rf /var/lib/apt/lists/* && \
        useradd -m -d /home/user -s /bin/bash -U -G sudo -u 1000 user && \
        echo 'user ALL=(ALL) NOPASSWD:ALL' >> /etc/sudoers && \
        mkdir /home/user/.ssh/

COPY    authorized_keys config id_ed25519 id_ed25519.pub known_hosts /home/user/.ssh/
COPY    sshd_config ssh_host_ed25519_key ssh_host_ed25519_key.pub /etc/ssh/

RUN     chown -R user:user /home/user/.ssh && \
        chmod 644 /home/user/.ssh/authorized_keys && \
        chmod 600 /home/user/.ssh/config && \
        chmod 600 /home/user/.ssh/id_ed25519 && \
        chmod 600 /home/user/.ssh/id_ed25519.pub && \
        chmod 600 /home/user/.ssh/known_hosts

RUN     chown root:root /etc/ssh/* && \
        chmod 644 /etc/ssh/sshd_config && \
        chmod 600 /etc/ssh/ssh_host_ed25519_key && \
        chmod 644 /etc/ssh/ssh_host_ed25519_key.pub      

RUN     service ssh start

EXPOSE  22

CMD     ["/usr/sbin/sshd","-D"]