post_install() {
  echo '==> Testing the kernel ...'
  /usr/bin/vnstat --testkernel
  echo '==> Every interface you want to monitor has to be introduced to vnStat!'
  echo '==> eg. vnstat -u -i eth0'
  echo '==> An example of a crontab to update vnStats database every 5 minutes'
  echo '==> has been put in /etc/cron.d/vnstat'
  /bin/true
}