anchor.diff:  
   RUN cd service/vpnet \
     && npm install
  -  
  +
   #
   #
   # END HEADER - VPNet.io
  
positive.code: FROM phusion/baseimage:0.9.19
  MAINTAINER AcrossFW <dev@acrossfw.com>
  
  #
  #
  # START HEADER - VPNet.io System Init
  
negative.code: #
  # inspired by https://github.com/vimagick/dockerfiles/tree/master/pptpd
  #
  # `rm pptpd.postinst` is a workaround of `no bus` error with systemd
  RUN apt-get update -qq && apt-get install -qqy \
        pptpd \
        || true \
  