added Dockerfile

Dockerfile

@@ -0,0 +1,30 @@
+# Use ubuntu 16.04
+FROM ubuntu:16.04
+EXPOSE 2020
+RUN apt-get update
+
+# install socat editor ssh
+RUN apt-get install socat -y
+
+RUN adduser --disabled-password --gecos "" ksl
+RUN echo "ksl:sebuahrahasiamas" | chpasswd
+
+RUN mkdir chall
+WORKDIR /chall
+
+# Secure ENV
+COPY flag.txt .
+COPY version002 .
+
+RUN echo 'alias kill="echo no kill please!"' >> ~/.bashrc
+RUN chmod 700 /tmp /usr/bin/* /bin/* /dev/shm
+# RUN chmod 755 /usr/bin/env /bin/dash /bin/bash /bin/sh /bin/nc /bin/cat /usr/bin/curl /usr/bin/groups /usr/bin/id /bin/ls /usr/bin/python /usr/bin/ruby
+
+RUN chown root:ksl /chall/version002
+RUN chmod 775 /chall/version002
+
+# Run Service
+
+RUN echo '#!/bin/bash'"\n(socat TCP-LISTEN:2020,reuseaddr,fork EXEC:"/chall/version002,su=nobody")" > /var/tmp/.start.sh && chmod +x /var/tmp/.start.sh
+
+CMD ["/var/tmp/.start.sh"]