This by way of a big "thumbs-up" for your book! well-done, thorough,
and even entertaining!
I've submitted to Slashdot to try and review it, but so far they haven't
responded. Maybe I need to bug them again.
Anyway, thanx to your book, I'm going to try the firewall idea on
OpenBSD (I've been more into Linux the past year or so) both to get a
feel for other ways of doing things as well as to broaden my horizons
and get another take on the whole security thing.
Besides, even if I decide to go with Linux for the firewall, the next
kernel looks like it adopts the two-stage approach to filtering/NATting.
Anyway, thanx again for great work! What have you got up your sleeve
for your next project(s)?