What are the hosting details and contrib guidelines?
And some other random notes…
“Best practices for securing Linux” could probably be dropped. There are enough of those, and the topic could overrun the focus on firewalls. I could see a secure network section, but Linux might be too broad.
What about opening it up to FOSS firewalls and networking in general? The BSDs, Illumos, Haiku, and others could be added. Linux could be the starting point, and the others could be added as people feel like it.