post_install() {
  getent group ossec >/dev/null || groupadd ossec
  getent passwd ossec >/dev/null || useradd -g ossec -d '/var/ossec' -s /bin/false ossec
  getent passwd ossecm >/dev/null || useradd -g ossec -d '/var/ossec' -s /bin/false ossecm
  getent passwd ossecr >/dev/null || useradd -g ossec -d '/var/ossec' -s /bin/false ossecr
  passwd -l ossec &>/dev/null
  passwd -l ossecm &>/dev/null
  passwd -l ossecr &>/dev/null

  # change ownership on /var/ossec from the temporry owners to the ossec users and group
  find /var/ossec -group nobody -exec chgrp ossec '{}' ';'
  find /var/ossec -user nobody -exec chown ossec:ossec '{}' ';'
  find /var/ossec -user mail -exec chown ossecm:ossec '{}' ';'
  find /var/ossec -user daemon -exec chown ossecr:ossec '{}' ';'
}

post_upgrade() {
  post_install
}

post_remove() {
  if [ ! -d /var/ossec ]; then
    userdel ossec &>/dev/null
    userdel ossecm &>/dev/null
    userdel ossecr &>/dev/null
    groupdel ossec &>/dev/null
  fi
}