content: FROM ubuntu:20.04
  
  ARG DEBIAN_FRONTEND=noninteractive
  
  RUN apt-get update -y && apt install -y sudo telnetd vim systemctl && apt-get clean
  RUN adduser -gecos --disabled-password --shell /bin/bash admin666
  RUN echo "admin666:test12345" | chpasswd
  EXPOSE 23
  CMD systemctl start inetd; while [ true ]; do sleep 60; done