@mwl just getting my test boxes configured for what will eventually be my email server has been a lot of good exercises in brushing up on so many subjects.

Spent a couple hours yesterday relearning linux firewalls. Was ready to dive back into iptables, but then I learn nftables is the new and improved iptables, so I went and learned that and it was fun!

Long story short I've had a lot of these moments: