Aide

Aide is an open source integrity monitor. Audit changes.

Install & Configure

 $ sudo apt install aide-common
 $ sudo aideinit
 $ sudo cp /var/lib/aide/aide.db.new /var/lib/aide/aide.db
 $ sudo update-aide.conf
 $ sudo cp /var/lib/aide/aide.conf.autogenerated /etc/aide/aide.conf

Verify

 $ sudo aide --version
 $ sudo aide --check

Test

 $ sudo mkdir /root/aide-test
 $ sudo touch /root/aide-test/test1
 $ sudo touch /root/aide-test/test2
 $ sudo aide -c /etc/aide/aide.conf --check

References

 https://help.ubuntu.com/community/FileIntegrityAIDE
 https://www.tecmint.com/check-integrity-of-file-and-directory-using-aide-in-linux/
 https://www.rapid7.com/blog/post/2017/06/30/how-to-install-and-configure-aide-on-ubuntu-linux/