anchor.diff:    && ln -s ${ACROSSFW_HOME}/service/vpnet /service/vpnet \
     && echo 'export WANIP=`curl -Ss ifconfig.io`' >> /etc/profile \
     && echo 'cd # fix $PWD=/acrossfw right after login bug? do not know why yet.' >> /root/.bashrc \
  -  && echo '[[ "$PS1" =~ WANIP ]] || PS1=${PS1//@\\\\h/@\\\\h(\$WANIP:-unknown-wan-ip)}' >> /root/.bashrc \
  +  && echo '[[ "$PS1" =~ WANIP ]] || PS1=${PS1//@\\\\h/@\\\\h(\$WANIP)}' >> /root/.bashrc \
     && echo '[[ "$PS1" =~ WANIP ]] || PS1=${PS1//@\\\\h/@\\\\h(\$WANIP)}' >> /etc/skel/.bashrc
   
   #
  
positive.code:     \
      && apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
  
  # PPTP Port must be standard(should not change?)
  EXPOSE 1723/tcp
  
  #
  # END PPTP
  
negative.code: # START PPTP
  #
  
  EXPOSE 1723/tcp # PPTP Port must be standard(should not change?)
  
  # https://groups.google.com/forum/#!topic/docker-user/dC6aIr4R1hY
  #
  # inspired by https://github.com/vimagick/dockerfiles/tree/master/pptpd
  