Ubuntu 18.04 Reaches End of Ubuntu Standard Support in April 2023

If you are running Security Onion 2.3 on Ubuntu 18.04, then you should be aware that Ubuntu 18.04 reaches the end of Ubuntu standard support in April 2023:
https://wiki.ubuntu.com/Releases

You should therefore start planning to upgrade or replace any Ubuntu 18.04 installations. We've added a guide to our documentation:
https://docs.securityonion.net/en/2.3/appendix-b.html