I've added to the above list 3 articles written by
Daniel Hartmeier, and related to
pf
[1]
Hartmeier D.,
Firewall Management, 2006[?] - [html]
[2]
Hartmeier D.,
Firewall Ruleset Optimization, 2006[?] - [html]
[3]
Hartmeier D.,
Testing Your Firewall, 2006[?] - [html]
BTW: I recommend His website
www.benzedrine.cx
Also added an interview with
Theo de Raadt, taken at ruBSD 2013